feat(toolchain): Add new make vars for Python interpreter path compliant with `--no_legacy_external_runfiles` by FrankPortman · Pull Request #2772

feat(toolchain): Add new make vars for Python interpreter path compliant with `--no_legacy_external_runfiles` by FrankPortman · Pull Request #2772 · bazel-contrib/rules_python

The change LGTM. I think the py2_runtime at some point should be dropped entirely.

Things that need to be done before this is merged:

Document the PYTHON3_ROOTPATH make var somewhere, this file seems to be a good place to do that.
Add :::versionchanged::: VERSION_NEXT_FEATURE line in the docstring for the rule, similar to how it is done elsewhere.
Add a line in the CHANGELOG about the added feature.
A test to ensure that this works is optional since we don't have any tests using the PYTHON3 var yet.

I might add these things if/when I have time myself, but if you want things to move quicker, please add these things.