fix: replace deprecated codecs.open with built-in open (#128)

[mvanhorn]

Fixes #128.

What changed

gitdb/db/ref.py:45 used codecs.open(self._ref_file, 'r', encoding="utf-8"). Replaced it with the built-in open(self._ref_file, 'r', encoding="utf-8") and dropped the now-unused import codecs.

Why this matters

Running the test suite under Python 3.14 emits the warning quoted in the issue:

gitdb/db/ref.py:45: DeprecationWarning: codecs.open() is deprecated. Use open() instead.
  with codecs.open(self._ref_file, 'r', encoding="utf-8") as f:

The built-in open() has accepted the encoding keyword since Python 3.0, and the call site already passed encoding="utf-8", so the replacement is byte-for-byte equivalent on every supported Python version. @Byron's comment on the issue ("if using open in its place is backwards compatible within the v3 version of python, this should be an easy fix") is exactly what this is.

Verification

• pytest gitdb/test/db/test_ref.py — 1 passed
• grep -rn 'codecs.open' --include='*.py' — 0 matches after the change

[Byron]

Thanks a lot, good catch!

[Copilot]

Pull request overview

This PR addresses Python 3.14 deprecation warnings by replacing usage of codecs.open() with the built-in open() when reading the reference file for ReferenceDB.

Changes:

• Remove the unused import codecs.
• Replace codecs.open(..., encoding="utf-8") with built-in open(..., encoding="utf-8") in _update_dbs_from_ref_file.

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