Stop using ubuntu 20.04

See actions/runner-images#11101

Author: cushon

.github/workflows/release.yml

@@ -91,10 +91,10 @@ jobs:
         # Use "oldest" available ubuntu-* instead of -latest,
         # see https://docs.github.com/en/actions/using-github-hosted-runners/about-github-hosted-runners/about-github-hosted-runners#standard-github-hosted-runners-for-public-repositories;
         # due to https://github.com/google/google-java-format/issues/1072.
-        os: [ubuntu-20.04, ubuntu-22.04-arm, macos-latest, windows-latest]
+        os: [ubuntu-22.04, ubuntu-22.04-arm, macos-latest, windows-latest]
     env:
         # NB: Must keep the keys in this inline JSON below in line with the os: above!
-      SUFFIX: ${{fromJson('{"ubuntu-20.04":"linux-x86-64", "ubuntu-22.04-arm":"linux-arm64", "macos-latest":"darwin-arm64", "windows-latest":"windows-x86-64"}')[matrix.os]}}
+      SUFFIX: ${{fromJson('{"ubuntu-22.04":"linux-x86-64", "ubuntu-22.04-arm":"linux-arm64", "macos-latest":"darwin-arm64", "windows-latest":"windows-x86-64"}')[matrix.os]}}
       EXTENSION: ${{ matrix.os == 'windows-latest' && '.exe' || '' }}
     steps:
       - name: "Check out repository"