use python venv; bug fixes; slight performance boost

What's Changed

• use a python venv by @2bndy5 in #173
• Bump actions/setup-python from 4 to 5 by @dependabot in #174
• Bump cpp-linter from 1.6.2 to 1.6.3 by @dependabot in #175

Full Changelog: v2...v2.7.3

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special thanks to @zjeffer for testing and feedback