Revert "Remove requires_python check"

This reverts commit e3d5f49.

Author: srittau

lib/ts_utils/metadata.py

@@ -269,6 +269,10 @@ def read_metadata(distribution: str) -> StubMetadata:
         assert type(requires_python_str) is str
         requires_python = Specifier(requires_python_str)
         assert requires_python != oldest_supported_python_specifier, f'requires_python="{requires_python}" is redundant'
+        # Check minimum Python version is not less than the oldest version of Python supported by typeshed
+        assert oldest_supported_python_specifier.contains(
+            requires_python.version
+        ), f"'requires_python' contains versions lower than typeshed's oldest supported Python ({oldest_supported_python})"
         assert requires_python.operator == ">=", "'requires_python' should be a minimum version specifier, use '>=3.x'"
 
     empty_tools: dict[object, object] = {}