Only run on ubuntu

Author: skshetry

.github/workflows/tests.yml

@@ -22,7 +22,10 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-20.04, windows-latest, macos-latest]
-        pyv: ['3.7', '3.8', '3.9', '3.10', 'pypy-3.8']
+        pyv: ['3.7', '3.8', '3.9', '3.10']
+        include:
+        - os: ubuntu-latest
+          pyv: 'pypy-3.8'
 
     steps:
     - name: Check out the repository