Merge pull request #1584 from riscv-software-src/debug-tests-ubuntu-20.04

Use Ubuntu 20.04 for debug tests

Author: aswaterman

.github/workflows/debug-smoke.yml

@@ -13,7 +13,7 @@ on:
 jobs:
   test:
     name: Test debug (Ubuntu)
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2