Omit 'if TYPE_CHECKING' blocks from coverage
Omit 'if TYPE_CHECKING' blocks from coverage

These blocks only exist to create code which evaluates under mypy
but does not run at runtime. As a result, they are impossible to cover
with `coverage` on a testsuite, and make sense to exclude from
coverage reporting.

python-jsonschema/jsonschema,Julian/jsonschema,Julian/jsonschema