feat: new primitive for weakref.ref

Author: BobTheBuidler

mypyc/test-data/run-weakref.test

@@ -1,6 +1,7 @@
 # Test cases for weakrefs (compile and run)
 
 [case testWeakrefRef]
+import pytest  # type: ignore [import-not-found]
 from weakref import ref
 from mypy_extensions import mypyc_attr