[python] Handle PEP 440 local prerelease versions

[gnufede]

What does this PR do?

Normalizes Python package versions returned by importlib.metadata.version("ddtrace") before ddtest's Python sanity check parses them.

dd-trace-py can publish PEP 440 prerelease/local versions like 4.12.0rc1+g0e3e598. ddtest's internal version parser expects semver-style prerelease syntax, so this PR converts those Python forms to parser-compatible values such as 4.12.0-rc1+g0e3e598 while leaving normal versions like 4.10.3 unchanged.

Motivation

When running the new Pytest/ddtest e2e flow from Shepherd against dd-trace-py@main, ddtest failed during platform sanity checking before planning tests:

invalid version component "0rc1"

That happened because the previous normalization handled 4.12.0rc1, but not the real source-build form with local metadata: 4.12.0rc1+g....

Additional Notes

The normalization stays in the Python platform layer instead of changing the shared version parser. This keeps the PEP 440 compatibility behavior scoped to Python package versions and avoids changing Ruby/JS/ddtest version semantics.

How to test the change?

Automated coverage was added for alpha, beta, rc, and local metadata cases, including the observed 4.12.0rc1+g0e3e598 shape.

Validated locally with:

go test ./internal/platform ./internal/version
go test ./...

[datadog-prod-us1-6]

 

🎉 All green!

🧪 All tests passed
❄️ No new flaky tests detected

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 87.65% (+0.00%)

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