Update black configuration

This is strictly not necessary, but what the hey.  Black no longer
supports the old `src_paths` configuration item, and it is good to
have *something* there to remind ourselves that black can be
configured this way.

pyproject.toml

@@ -5,7 +5,7 @@ lint = [
 ]
 
 [tool.black]
-src_paths = ["setup.py", "swagger_server", "bapm_server"]
+include = '\.py?$'
 
 [tool.isort]
 profile = "black"