chore(python): removes a filter put in place due to a dependency issue with pyarrow (#2338)

Due to an issue with `pyarrow`, a significant dependency for certain
python-bigquery use cases, not being compatible with Python 3.14, we
temporarily skipped the failing CI/CD check for 3.14 while awaiting the
update to pyarrow. Pyarrow is now fully compatible, so that filter is
being removed.

**KNOWN ISSUES**: this will show that unittests for 3.14 are failing.
This has nothing to do with this PR/these changes. It is being addressed
in an alternate mod. It is due to a missing dependency related to
handling IO for `geopandas` (namely it is missing `libgdal-dev`, etc
which are normally installed with `pyogrio` + `geopandas`). Because
`pyogrio` is currently not compatible with Python 3.14 the tests in 3.14
cannot complete.

This should not prevent **this PR from being merged** to help solve the
current issue, which is a blocker for getting our continuous tests to
green.

Author: chalmerlowe

.github/workflows/unittest.yml

@@ -21,12 +21,6 @@ jobs:
         python -m pip install --upgrade setuptools pip wheel
         python -m pip install nox
     - name: Run unit tests
-
-      # TODO (https://b.corp.google.com/issues/450370502) 3.14 is not yet supported by pyarrow. See
-      # https://github.com/googleapis/google-cloud-python/issues/14686
-      # https://github.com/apache/arrow/issues/47438
-      # Reinstate running tests with 3.14 once this bug is fixed
-      if: matrix.python != '3.14'
       env:
         COVERAGE_FILE: .coverage-${{ matrix.python }}
       run: |