Update workflow to use ubuntu-latest

Author: grantcopley

.github/workflows/pr.yml

@@ -12,7 +12,7 @@ jobs:
   #############################################
   tests:
     name: Tests
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     env:
       MODULE_ID: cbwire
     strategy:
@@ -92,7 +92,7 @@ jobs:
 
   format:
     name: Format
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     steps:
       - name: Checkout Repository
         uses: actions/checkout@v2