Add stubs for rfc3339-validator (#13688)

stubs/rfc3339-validator/METADATA.toml

@@ -0,0 +1,2 @@
+version = "0.1.*"
+upstream_repository = "https://github.com/naimetti/rfc3339-validator"

stubs/rfc3339-validator/rfc3339_validator.pyi

@@ -0,0 +1,10 @@
+import re
+from typing import Final
+
+__version__: Final[str]
+__author__: Final[str]
+__email__: Final[str]
+RFC3339_REGEX_FLAGS: Final[int]
+RFC3339_REGEX: Final[re.Pattern[str]]
+
+def validate_rfc3339(date_string: str) -> bool: ...