Update check.yml

Author: gaborbernat

.github/workflows/check.yml

@@ -33,7 +33,7 @@ jobs:
           - "3.8"
           - "3.7"
           - "3.6"
-          - "pypy-3.6-v7.3.3"
+          - "pypy-3.7-v7.3.7"
 
     steps:
       - name: Setup python for tox