Add back Python 3.7 test configs

Author: astrofrog

.github/workflows/ci_workflows.yml

@@ -12,8 +12,8 @@ jobs:
     uses: OpenAstronomy/github-actions-workflows/.github/workflows/tox.yml@v1
     with:
       envs: |
-        - linux: py38-test-pytest46
-        - macos: py38-test-pytest50
+        - linux: py37-test-pytest46
+        - macos: py37-test-pytest50
         - windows: py38-test-pytest52
         - linux: py38-test-pytest53
         - macos: py39-test-pytest60