Drop CI for EOLd Python 3.7

.github/workflows/ci.yml

@@ -33,7 +33,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
-        python: ['3.11', '3.10', '3.9', '3.8', '3.7'] # pypy3
+        python: ['3.11', '3.10', '3.9', '3.8'] # pypy3
 
     steps:
     - uses: actions/checkout@v3