Pin ubuntu version for github workflow to 20.04.

Author: gkhaburzaniya-onelogin

.github/workflows/python-package.yml

@@ -13,7 +13,7 @@ on:
 
 jobs:
   test:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     strategy:
       fail-fast: false
       matrix:
@@ -47,7 +47,7 @@ jobs:
     - name: Test
       run: make pytest
   lint:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
     - uses: actions/checkout@v2
     - uses: actions/setup-python@v2