Use lowercase tuple where possible (#6170)

stdlib/lib2to3/pytree.pyi

@@ -68,7 +68,7 @@ class BasePattern:
     def optimize(self) -> BasePattern: ...  # sic, subclasses are free to optimize themselves into different patterns
     def match(self, node: _NL, results: _Results | None = ...) -> bool: ...
     def match_seq(self, nodes: list[_NL], results: _Results | None = ...) -> bool: ...
-    def generate_matches(self, nodes: list[_NL]) -> Iterator[Tuple[int, _Results]]: ...
+    def generate_matches(self, nodes: list[_NL]) -> Iterator[tuple[int, _Results]]: ...
 
 class LeafPattern(BasePattern):
     def __init__(self, type: int | None = ..., content: str | None = ..., name: str | None = ...) -> None: ...
@@ -85,4 +85,4 @@ class WildcardPattern(BasePattern):
 class NegatedPattern(BasePattern):
     def __init__(self, content: str | None = ...) -> None: ...
 
-def generate_matches(patterns: list[BasePattern], nodes: list[_NL]) -> Iterator[Tuple[int, _Results]]: ...
+def generate_matches(patterns: list[BasePattern], nodes: list[_NL]) -> Iterator[tuple[int, _Results]]: ...