remove mypy constraint

Author: parthea

noxfile.py

@@ -275,9 +275,7 @@ def pytype(session):
 @nox.session(python=DEFAULT_PYTHON_VERSION)
 def mypy(session):
     """Run type-checking."""
-    # TODO(https://github.com/googleapis/python-api-core/issues/799):
-    # Remove mypy constraint. We should use the latest version of mypy.
-    session.install(".[grpc,async_rest]", "mypy<1.15.0")
+    session.install(".[grpc,async_rest]", "mypy")
     session.install(
         "types-setuptools",
         "types-requests",