refactor: update PyVenvCfg to use Option types for version fields and… #1287

Job	Run time
Env Tests (ci-poetry-global, windows-latest, x86_64-pc-windows-msvc)	7m 38s
Tests (macos-14, aarch64-apple-darwin, yes)	12m 54s
Env Tests (ci-poetry-project, ubuntu-latest, x86_64-unknown-linux-musl)	2m 53s
Builds (macos-14, aarch64-apple-darwin, yes)	2m 15s
Env Tests (ci-poetry-project, windows-latest, x86_64-pc-windows-msvc)	6m 11s
Tests in Containers (ci-homebrew-container, ubuntu-latest, homebrew/brew, x86_64-unknown-linux-musl)	3m 48s
Tests (windows-latest, x86_64-pc-windows-msvc, yes)	7m 30s
Env Tests (ci-poetry-custom, windows-latest, x86_64-pc-windows-msvc)	6m 3s
Builds (windows-latest, aarch64-pc-windows-msvc)	4m 41s
Builds (ubuntu-latest, x86_64-unknown-linux-musl, yes)	2m 10s
Tests (macos-latest, x86_64-apple-darwin, yes)	14m 27s
Env Tests (ci-poetry-global, ubuntu-latest, x86_64-unknown-linux-musl)	2m 40s
Builds (windows-latest, x86_64-pc-windows-msvc)	5m 15s
Builds (macos-latest, x86_64-apple-darwin, yes)	2m 27s
Env Tests (ci-poetry-custom, ubuntu-latest, x86_64-unknown-linux-musl)	2m 44s
Tests (ubuntu-latest, x86_64-unknown-linux-musl, yes)	9m 21s
Tests in Containers (ci-jupyter-container, ubuntu-latest, mcr.microsoft.com/devcontainers/univers...	4m 34s
	1h 37m 31s

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