fix(bazel): use Label() for deps in py_itf_unittest

[clanghans]

Summary

The py_itf_unittest macro passes "@score_itf//:itf" and "@itf_pip//pytest_mock" as string labels in the deps list of py_test. In Bazel's bzlmod, string labels inside legacy (def-based) macros are resolved in the caller's repository context, not the defining module's. This means @itf_pip is looked up in the downstream consumer's repo, where it does not exist.

The fix wraps both labels with Label(), which is evaluated at .bzl load time and resolves in score_itf's module context, where itf_pip is always defined.

This is consistent with how pytest_bootstrap and pytest_config are already handled in the same file (lines 33-35).

Problem

Any downstream module that uses py_itf_unittest fails at analysis time:

ERROR: no such package '@@[unknown repo 'itf_pip' requested from @@]//pytest_mock':
  The repository '@@[unknown repo 'itf_pip']' could not be resolved:
  No repository visible as '@itf_pip' from main repository

The only workaround is for every consumer to add use_repo(pip, "itf_pip") to their own MODULE.bazel, leaking an internal implementation detail of score_itf into all downstream modules.

Benefits

• Downstream consumers no longer need to know about @itf_pip. The pip hub name is an internal detail of score_itf. Consumers should only need bazel_dep(name = "score_itf", ...) to use any public macro.

• Consistent with the rest of the file. pytest_bootstrap and pytest_config already use Label(). The deps list was the only place still using raw strings for cross-module references.

• No behavioral change for score_itf's own tests. Label("@itf_pip//...") resolves to the same target within score_itf as the string "@itf_pip//..." does today. The fix only changes resolution behavior when the macro is called from a different module.

[a-zw]

LGTM

Similar PR in docs-as-code.