Unit test coverage gap when running 3.14

I'm hitting a strange issue where there is a coverage gap in python 3.14 in unit tests, but in all other python runtimes there is no gap. See https://github.com/googleapis/gapic-generator-python/actions/runs/18045136023/job/51353943485?pr=2344

```
ERROR: Coverage failure: total of 99 is less than fail-under=100

================================ tests coverage ================================
_____________ coverage: platform linux, python 3.14.0-candidate-3 ______________

Name Stmts Miss Branch BrPart Cover Missing
---------------------------------------------------------------------------------------------------
gapic/configurable_snippetgen/__init__.py 0 0 0 0 100%
gapic/configurable_snippetgen/configured_snippet.py 103 0 18 0 100%
gapic/configurable_snippetgen/libcst_utils.py 27 0 6 0 100%
gapic/generator/__init__.py 2 0 0 0 100%
gapic/generator/formatter.py 6 0 0 0 100%
gapic/generator/generator.py 131 0 48 0 100%
gapic/samplegen/__init__.py 3 0 0 0 100%
gapic/samplegen/manifest.py 20 0 2 0 100%
gapic/samplegen/samplegen.py 383 0 158 0 100%
gapic/samplegen_utils/__init__.py 4 0 0 0 100%
gapic/samplegen_utils/snippet_index.py 80 0 24 0 100%
gapic/samplegen_utils/types.py 64 0 8 0 100%
gapic/samplegen_utils/utils.py 28 0 8 0 100%
gapic/samplegen_utils/yaml.py 38 0 0 0 100%
gapic/schema/__init__.py 4 0 0 0 100%
gapic/schema/api.py 471 0 160 1 99% 938->943
gapic/schema/imp.py 16 0 6 0 100%
gapic/schema/metadata.py 129 0 46 0 100%
gapic/schema/mixins.py 2 0 0 0 100%
gapic/schema/naming.py 76 0 20 0 100%
gapic/schema/wrappers.py 867 0 246 0 100%
gapic/templates/_license.j2 0 0 0 0 100%
gapic/templates/examples/_generated_sample_comment.j2 0 0 0 0 100%
gapic/utils/__init__.py 19 0 0 0 100%
gapic/utils/cache.py 10 0 4 0 100%
gapic/utils/case.py 10 0 0 0 100%
gapic/utils/checks.py 5 0 0 0 100%
gapic/utils/code.py 14 0 2 0 100%
gapic/utils/doc.py 3 0 0 0 100%
gapic/utils/filename.py 5 0 0 0 100%
gapic/utils/lines.py 58 0 30 0 100%
gapic/utils/options.py 76 0 22 0 100%
gapic/utils/reserved_names.py 1 0 0 0 100%
gapic/utils/rst.py 13 0 6 0 100%
gapic/utils/uri_conv.py 19 0 4 0 100%
gapic/utils/uri_sample.py 30 0 6 0 100%
---------------------------------------------------------------------------------------------------
TOTAL 2717 0 824 1 99%
FAIL Required test coverage of 100% not reached. Total coverage: 99.97%
============================= 625 passed in 6.63s ==============================
nox > Command py.test -vv -n=auto --cov=gapic --cov-config=.coveragerc --cov-report=term --cov-fail-under=100 tests/unit failed with exit code 1
nox > Session unit-3.14 failed.
```