[ci] enforce perflint checks

[jameslamb]

Proposes enforcing the perflint checks in this project's CI.

Fixes the following:

src/pydistcheck/checks.py:122:29: PERF102 When using only the values of a dict use the `values()` method
tests/test_distribution_summary.py:86:29: PERF102 When using only the values of a dict use the `values()` method
tests/test_distribution_summary.py:203:29: PERF102 When using only the values of a dict use the `values()` method

For more, see https://github.com/tonybaloney/perflint and https://docs.astral.sh/ruff/rules/#perflint-perf.