Add CI job for pypy 3.7

Author: cdce8p

.github/workflows/ci.yaml

@@ -336,7 +336,7 @@ jobs:
     timeout-minutes: 10
     strategy:
       matrix:
-        python-version: ["pypy-3.6"]
+        python-version: ["pypy-3.6", "pypy-3.7"]
     outputs:
       python-key: ${{ steps.generate-python-key.outputs.key }}
     steps:
@@ -381,7 +381,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["pypy-3.6"]
+        python-version: ["pypy-3.6", "pypy-3.7"]
     steps:
       - name: Check out code from GitHub
         uses: actions/[email protected]