chore(run): transform comment into docstring

Author: pabloyoyoista

src/pipx/commands/run.py

@@ -44,8 +44,8 @@
 
 
 def maybe_script_content(app: str, is_path: bool) -> Optional[Union[str, Path]]:
-    # If the app is a script, return its content.
-    # Return None if it should be treated as a package name.
+    """If the app is a script, return its content.
+    Return None if it should be treated as a package name."""
 
     # Look for a local file first.
     app_path = Path(app)