fix: make parse_base_url return str as annotated

It returned Path(workspace).parent — a Path — despite the
declared str return type. Resolves the mypy return-value error.

src/byteb4rb1e/utils/vcs/git.py

@@ -41,7 +41,7 @@ def parse_base_url(base_url: str) -> str:
             f"got: {base_url}"
         )
     _, workspace = base_url.split(":", 1)
-    return Path(workspace).parent
+    return str(Path(workspace).parent)
 
 
 def parse_repo_name(base_url: str) -> str: