Merge pull request #2595 from cta-observatory/fix_docs_build

Fix provenance in case broken packages are in the environment

src/ctapipe/core/provenance.py

@@ -306,7 +306,7 @@ def provenance(self):
 def _get_python_packages():
     return [
         {"name": p.name, "version": p.version}
-        for p in sorted(distributions(), key=lambda d: d.name)
+        for p in sorted(distributions(), key=lambda d: (d.name or "").lower())
     ]