Mark python-crontab as completed (#8938)

stubs/python-crontab/@tests/stubtest_allowlist.txt

@@ -0,0 +1,2 @@
+# Re-export:
+crontabs.X_OK

stubs/python-crontab/METADATA.toml

@@ -1 +1,4 @@
 version = "2.6.*"
+
+[tool.stubtest]
+ignore_missing_stub = false

stubs/python-crontab/cronlog.pyi

@@ -2,7 +2,9 @@ from _typeshed import Self, StrOrBytesPath
 from codecs import StreamReaderWriter
 from collections.abc import Generator, Iterator
 from types import TracebackType
+from typing_extensions import Literal
 
+PY3: Literal[True]
 MATCHER: str
 
 class LogReader: