chore: access ctx.version_file to inform Bazel stamping info is needed (#1952)

This enables an optimization in Bazel et al to better track when targets
actually need stamping information. Accessing the `ctx.version_file`
tells Bazel the target depends on stamping information, which related
systems can use to optimize processing of the build graph.

Author: rickeylev

python/private/common/py_executable.bzl

@@ -243,6 +243,9 @@ def py_executable_base_impl(ctx, *, semantics, is_test, inherited_environment =
 def _get_build_info(ctx, cc_toolchain):
     build_info_files = py_internal.cc_toolchain_build_info_files(cc_toolchain)
     if cc_helper.is_stamping_enabled(ctx):
+        # Makes the target depend on BUILD_INFO_KEY, which helps to discover stamped targets
+        # See b/326620485 for more details.
+        ctx.version_file  # buildifier: disable=no-effect
         return build_info_files.non_redacted_build_info_files.to_list()
     else:
         return build_info_files.redacted_build_info_files.to_list()