github: workflows: main: Use ubuntu-20.04 over latest

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

Author: patrickelectric

.github/workflows/main.yml

@@ -36,7 +36,7 @@ jobs:
     name: Create release and upload artifacts
     needs:
       - build-and-test
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - name: Download artifacts
         uses: actions/download-artifact@v2