Revert "Update action runner image as part of this issue actions/runner-images#11101"

This reverts commit c91fae2.

Author: gyear

.github/workflows/linting.yml

@@ -2,7 +2,7 @@ name: Static Analysis
 on: [pull_request]
 jobs:
   python-linting:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-20.04
     steps:
     - uses: actions/checkout@v2
 

.github/workflows/unit_tests.yml

@@ -2,7 +2,7 @@ name: easyconfigs unit tests
 on: [pull_request]
 jobs:
   test-suite:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-20.04
     strategy:
       matrix:
         python: [3.6]