fix linux build (#410)

Author: gijzelaerr

.github/workflows/linux.yml

@@ -6,10 +6,10 @@ on:
     branches: [master]
 jobs:
   build:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     strategy:
       matrix:
-        python-version: ["3.7", "3.8", "3.9", "3.10"]
+        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11"]
     steps:
       - name: Checkout
         uses: actions/checkout@v2