workflows/tests: use the brew image unless specific Ubuntu version …

…is needed

Co-authored-by: Mike McQuaid <[email protected]>

.github/workflows/tests.yml

@@ -140,7 +140,7 @@ jobs:
     if: github.repository_owner == 'Homebrew'
     runs-on: ubuntu-latest
     container:
-      image: ghcr.io/homebrew/ubuntu22.04:master
+      image: ghcr.io/homebrew/brew:master
     steps:
       - name: Set up Homebrew
         id: set-up-homebrew
@@ -251,11 +251,11 @@ jobs:
           - name: tests (online)
             test-flags: --online --coverage
             runs-on: ubuntu-latest
-            container: ghcr.io/homebrew/ubuntu22.04:master
+            container: ghcr.io/homebrew/brew:master
           - name: tests (generic OS)
             test-flags: --generic --coverage
             runs-on: ubuntu-latest
-            container: ghcr.io/homebrew/ubuntu22.04:master
+            container: ghcr.io/homebrew/brew:master
           - name: tests (Ubuntu 22.04)
             test-flags: --coverage
             runs-on: ubuntu-latest