Replace deprecated save-always with cache/restore + cache/save

[tautschnig]

The actions/cache save-always input has been deprecated and will be removed in a future release. Replace all occurrences of actions/cache@v5 with save-always: true by a pair of actions/cache/restore@v5 (to restore) and actions/cache/save@v5 (with if: always(), to unconditionally save) steps.

This follows the pattern established in the profiling workflow and the recommendation at
https://github.com/actions/cache/tree/main/save#always-save-cache.

• Each commit message has a non-empty body, explaining why the change was made.
• n/a Methods or procedures I have added are documented, following the guidelines provided in CODING_STANDARD.md.
• n/a The feature or user visible behaviour I have added or modified has been documented in the User Guide in doc/cprover-manual/
• Regression or unit tests are included, or existing tests cover the modified code (in this case I have detailed which ones those are in the commit message).
• n/a My commit message includes data points confirming performance improvements (if claimed).
• My PR is restricted to a single feature or bugfix.
• n/a White-space or formatting changes outside the feature-related changed lines are in commits of their own.

[Copilot]

Pull request overview

This PR updates CI workflows to remove usage of the deprecated actions/cache@v5 save-always: true input by switching to the recommended actions/cache/restore@v5 + actions/cache/save@v5 (guarded with if: always()) pattern.

Changes:

• Replaced actions/cache@v5 steps that used save-always: true with actions/cache/restore@v5 restore steps.
• Added corresponding actions/cache/save@v5 steps at the end of each affected job to ensure caches are saved even when the job fails.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
.github/workflows/release-packages.yaml	Switch ccache caching to restore/save split for release packaging jobs (Linux + Windows).
.github/workflows/pull-request-checks.yaml	Switch ccache caching to restore/save split across the main PR CI matrix jobs.
.github/workflows/pull-request-check-rust-api.yaml	Switch ccache caching to restore/save split for Rust API PR checks.
.github/workflows/csmith.yaml	Switch ccache caching to restore/save split for Csmith workflow.
.github/workflows/coverage.yaml	Switch ccache caching to restore/save split for coverage workflow.
.github/workflows/build-and-test-Xen.yaml	Switch ccache caching to restore/save split for Xen build/test workflow.
.github/workflows/build-and-test-Linux.yaml	Switch ccache caching to restore/save split for Linux build/test workflow.
.github/workflows/bsd.yaml	Switch ccache caching to restore/save split for BSD workflows.

Comments suppressed due to low confidence (3)

.github/workflows/release-packages.yaml:36

• restore-keys is written as an indented block without | (multiline string) or - (YAML list). In YAML this gets parsed as a single folded scalar, so actions/cache/restore will effectively receive one restore-key instead of the intended two. Use a restore-keys: | block (or a proper YAML sequence) so each prefix is a separate restore key.

          restore-keys:
            ${{ runner.os }}-24.04-Release-${{ github.ref }}
            ${{ runner.os }}-24.04-Release

.github/workflows/release-packages.yaml:108

• restore-keys is written as an indented block without | (multiline string) or - (YAML list). In YAML this gets parsed as a single folded scalar, so actions/cache/restore will effectively receive one restore-key instead of the intended two. Use a restore-keys: | block (or a proper YAML sequence) so each prefix is a separate restore key.

          restore-keys:
            ${{ runner.os }}-24.04-Arm-Release-${{ github.ref }}
            ${{ runner.os }}-24.04-Arm-Release

.github/workflows/release-packages.yaml:180

• restore-keys is written as an indented block without | (multiline string) or - (YAML list). In YAML this gets parsed as a single folded scalar, so actions/cache/restore will effectively receive one restore-key instead of the intended two. Use a restore-keys: | block (or a proper YAML sequence) so each prefix is a separate restore key.

          restore-keys:
            ${{ runner.os }}-22.04-Release-${{ github.ref }}
            ${{ runner.os }}-22.04-Release

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.56%. Comparing base (808dae2) to head (6168492).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #8891   +/-   ##
========================================
  Coverage    80.55%   80.56%           
========================================
  Files         1707     1707           
  Lines       189051   189051           
  Branches        73       73           
========================================
+ Hits        152299   152302    +3     
+ Misses       36752    36749    -3     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.