Launch user scripts with run_name == "__main__"

Launches the user-provided scripts with a more canonical `__name__` parameter.

mkdocs_gen_files/plugin.py

@@ -35,7 +35,7 @@ def on_files(self, files: Files, config: MkDocsConfig) -> Files:
         with FilesEditor(files, config, self._dir.name) as ed:
             for file_name in self.config.scripts:
                 try:
-                    runpy.run_path(file_name)
+                    runpy.run_path(file_name, run_name="__main__")
                 except SystemExit as e:
                     if e.code:
                         raise PluginError(f"Script {file_name!r} caused {e!r}")