Add types to file generated by __test__.py

[antspy]

I am adding types to user_args otherwise mypy complains when running bazel test.

I am trying to automatically run mypy when building my bazel targets. I am using rules_mypy for this.
I am also using the py_pytest_main rule:

py_pytest_main(
    name = "__test__",
    deps = ["@pip//pytest"],
)

py_test(
    name = "mytest",
    size = "small",
    srcs = [
        "mytest.py",
        ":__test__",
    ],
    main = ":__test__.py",
    package_collisions = "warning",
    deps = [
        ":__test__",
        ":mylib",
    ],
)

However, if I run bazel test mytest, mypy complains: bazel-out/k8-fastbuild/bin/src/backend2/__test__.py:42: error: Need type annotation for "user_args" (hint: "user_args: list[<type>] = ...") [var-annotated].
I haven't found a way to remove the __test__ file from mypy analysis, and this is actually a simple fix, so I thought we could patch this in.

---

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• Searched for relevant documentation and updated as needed: no
• Breaking change (forces users to change their own code or config): no
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[mattem]

Thanks!

[mattem]

Sorry, this got reverted as it's not compatible with older versions of Python it seems. I didn't notice that CI didn't run on this diff, and it caused main to go red.

I think we should be able to template this file so that we can take the Python version into account when adding type annotations.