Improve cmp_op in opcode (#6884)

stdlib/opcode.pyi

@@ -1,7 +1,23 @@
 import sys
-from typing import Sequence
+from typing_extensions import Literal
 
-cmp_op: Sequence[str]
+if sys.version_info >= (3, 9):
+    cmp_op: tuple[Literal["<"], Literal["<="], Literal["=="], Literal["!="], Literal[">"], Literal[">="]]
+else:
+    cmp_op: tuple[
+        Literal["<"],
+        Literal["<="],
+        Literal["=="],
+        Literal["!="],
+        Literal[">"],
+        Literal[">="],
+        Literal["in"],
+        Literal["not in"],
+        Literal["is"],
+        Literal["is not"],
+        Literal["exception match"],
+        Literal["BAD"],
+    ]
 hasconst: list[int]
 hasname: list[int]
 hasjrel: list[int]