Fix annotation for misc.UseExisting to be Final to avoid reassignment without warnings from a type checker.

- Also add a noqa to _mixin.URIMixin.resolve_with, since the extra `if TYPE_CHECKING`` statement pushed it over the complexity limit.

Co-authored-by: Ian Stapleton Cordasco <graffatcolmingov@gmail.com>

Author: Sachaa-Thanasius

src/rfc3986/_mixin.py

@@ -270,7 +270,7 @@ def normalized_equality(self, other_ref: "uri.URIReference") -> bool:
         """
         return tuple(self.normalize()) == tuple(other_ref.normalize())
 
-    def resolve_with(
+    def resolve_with(  # noqa: C901
         self,
         base_uri: t.Union[str, "uri.URIReference"],
         strict: bool = False,

src/rfc3986/misc.py

@@ -136,4 +136,4 @@ def merge_paths(base_uri: URIReferenceBase, relative_path: str) -> str:
         return path[:index] + "/" + relative_path
 
 
-UseExisting: t.Any = object()
+UseExisting: t.Final[t.Any] = object()