test: Fix `exclude_lines` for coverage
`exclude_lines` was only considering TYPE_CHECKING if it was preceded
with at least one space.
@@ -39,7 +39,7 @@ exclude_lines =
pragma: no cover
# TYPE_CHECKING guarded code only affects type checkers.
- ^ +if (False|TYPE_CHECKING):
+ ^ *if (False|TYPE_CHECKING):
# constant used in protocols and abstract methods, does not run anything
# and has no side effects.
^ +\.\.\.$
