github: Bump ubuntu version for standalone

Author: remko

.github/workflows/build-waforthc.yml

@@ -10,7 +10,7 @@ jobs:
   build-waforthc:
     strategy:
       matrix:
-        os: [macos-latest, ubuntu-20.04]
+        os: [macos-latest, ubuntu-latest]
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v3

.github/workflows/publish-waforthc.yml

@@ -12,7 +12,7 @@ jobs:
     needs: build
     strategy:
       matrix:
-        os: [macos-latest, ubuntu-20.04]
+        os: [macos-latest, ubuntu-latest]
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v3