chore: PP309: Filter warnings specified

Apply repo-review suggestion PP309:
	filterwarnings must be set (probably to at least ["error"]).
	Python will hide important warnings otherwise, like deprecations.

pyproject.toml

@@ -198,6 +198,7 @@ testpaths = ["tests"]
 markers = [
     "network: mark tests that require internet access",
 ]
+filterwarnings = ["error"]
 
 
 [tool.coverage.report]