test: add unit tests for pet-pyenv crate (Fixes #389) (#441) #1548

Job	Run time
Tests (windows-latest, x86_64-pc-windows-msvc, yes)	8m 54s
Env Tests (ci-poetry-project, windows-latest, x86_64-pc-windows-msvc)	7m 35s
Builds (windows-latest, x86_64-pc-windows-msvc)	5m 24s
Env Tests (ci-poetry-global, ubuntu-latest, x86_64-unknown-linux-musl)	2m 59s
Tests in Containers (ci-homebrew-container, ubuntu-latest, homebrew/brew, x86_64-unknown-linux-musl)	58s
Env Tests (ci-poetry-custom, ubuntu-latest, x86_64-unknown-linux-musl)	3m 11s
Tests (macos-14, aarch64-apple-darwin, yes)	12m 36s
Builds (macos-14, aarch64-apple-darwin, yes)	3m 6s
Builds (ubuntu-latest, x86_64-unknown-linux-musl, yes)	2m 27s
Tests (ubuntu-latest, x86_64-unknown-linux-musl, yes)	9m 52s
Builds (macos-latest, x86_64-apple-darwin, yes)	3m 48s
Env Tests (ci-poetry-global, windows-latest, x86_64-pc-windows-msvc)	6m 33s
Env Tests (ci-poetry-custom, windows-latest, x86_64-pc-windows-msvc)	7m 0s
Tests in Containers (ci-jupyter-container, ubuntu-latest, mcr.microsoft.com/devcontainers/univers...	4m 22s
Env Tests (ci-poetry-project, ubuntu-latest, x86_64-unknown-linux-musl)	2m 59s
Tests (macos-latest, x86_64-apple-darwin, yes)	13m 17s
Builds (windows-latest, aarch64-pc-windows-msvc)	4m 15s
	1h 39m 16s

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