reduce number of tests

Author: 1adrianb

.github/workflows/python-package.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [3.7, 3.8, 3.9]
+        python-version: [3.7, 3.8]
         pytorch-version: [1.8.1, nightly]
     steps:
       - uses: actions/checkout@v2