Remove unused ignore (#2087)

Author: sobolevn

setup.cfg

@@ -145,9 +145,6 @@ enable_error_code =
   possibly-undefined,
   redundant-self,
 
-# We run mypy on all python versions, but only 3.10+ supports pattern matching:
-exclude = .*test_.*pattern_matching
-
 disable_error_code = empty-body, no-untyped-def
 
 # We cannot work without explicit `Any` types and plain generics: