Add py.typed file to make test_project_python PEP 561 compliant

- this change addresses the following regression from the previous commit:
/path/to/test_project/python/test_project_python_tests/test_package_builder.py:4:1:4:1: error: Skipping analyzing "test_project_python.package_builder": module is installed, but missing library stubs or py.typed marker  [import]
    from test_project_python.package_builder import (
    ^
/path/to/test_project/python/test_project_python_tests/test_package_builder.py:4:1:4:1: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
- removing the `os.chdir()` commands are safe now since the `py.typed` file
  allows `mypy` to analyze the `import`ed `test_project_python` package
  without running into the error above
  - see the previous commit for more information about why
    manually moving into the `python` directory might be problematic

python/pre_commit.py

@@ -34,7 +34,6 @@ def static_type_check_packages_and_modules(
     # directory, so this module needs to move into the
     # test_project/python directory in order to find the
     # test_project_python and test_project_python_tests packages
-    # os.chdir('python') # change into python directory to allow mypy to find test_project_python package
     mypy_flags = [
         '--strict',
         '--show-error-context',
@@ -51,7 +50,6 @@ def static_type_check_packages_and_modules(
         current_config = mypy_flags + package_config
         print(f'''mypy {' '.join(current_config)}''')
         mypy.main.main(args=current_config, clean_exit=True)
-    # os.chdir('..')   # change back to root directory to allow relative paths to work properly from pre-commit hook (which runs from the root directory of the git repo)
     for changed_py_file in changed_py_files:
         current_config = mypy_flags + [changed_py_file]
         print(f'''mypy {' '.join(current_config)}''')

python/setup.py

@@ -76,7 +76,7 @@
     # If there are data files included in your packages that need to be installed, specify them here.
     # If using Python 2.6 or earlier, then these have to be included in MANIFEST.in as well.
     package_data = {  # Optional
-        # 'sample': ['package_data.dat'],
+        'test_project_python': ['py.typed'],
     },
     # Although 'package_data' is the preferred approach, in some case you may need to place data files outside of your packages. See:
     # http://docs.python.org/3.4/distutils/setupscript.html#installing-additional-files

python/test_project_python/py.typed

@@ -0,0 +1,24 @@
+'''
+This py.typed file makes this package (test_project_python)
+a PEP 561 compliant stub package.
+
+Make sure to add a `package_data` argument consisting of
+a `dict` with the key(s) corresponding to the package name(s)
+and the value(s) corresponding to the file(s) in that package
+that contain the type hint information to the `setup`
+function (e.g. in `distutils.core.setup` or `setuptools.setup`).
+If the type hint information is contained in inline type annotations,
+a `py.typed` file should suffice.
+
+```
+package_data={"package_name": ["py.typed"]},
+# OR if the package has stub files (ending in .pyi)
+package_data={"package_name": ["py.typed", "module1.pyi", "module2.pyi"]},
+```
+
+Read the following for more information:
+- https://mypy.readthedocs.io/en/stable/installed_packages.html
+- https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-library-stubs-or-py-typed-marker
+- https://mypy.readthedocs.io/en/stable/stubs.html#stub-files
+- https://peps.python.org/pep-0561/
+'''