Allow three-component third-party versions (#5995)

Closes: #5992

tests/check_consistent.py

@@ -169,9 +169,7 @@ def check_metadata():
         assert "version" in data, f"Missing version for {distribution}"
         version = data["version"]
         msg = f"Unsupported Python version {version}"
-        assert version.count(".") == 1, msg
-        major, minor = version.split(".")
-        assert major.isdigit() and minor.isdigit(), msg
+        assert re.match(r"^\d+\.\d+(\.\d+)?$", version), msg
         for key in data:
             assert key in metadata_keys, f"Unexpected key {key} for {distribution}"
         assert isinstance(data.get("python2", False), bool), f"Invalid python2 value for {distribution}"