Bug 1561187 [wpt PR 17460] - Update mypy to 0.711, a=testonly

Automatic update from web-platform-tests
Update mypy from 0.710 to 0.711
--

wpt-commits: 41be99f198f2937103f8af00642cce91c9e48826
wpt-pr: 17460

testing/web-platform/tests/tools/requirements_mypy.txt

@@ -1,3 +1,3 @@
-mypy==0.710
+mypy==0.711
 mypy-extensions==0.4.1
 typed-ast==1.4.0