docker, actions: Update for Ubuntu 24.04 (#39548)

GitHub is preparing to roll out Ubuntu 24.04 to Actions. This prepares
us for that.

* Update our own Docker development environment to be based on 24.04.
* `svn` has been removed from the default Actions image. Install it
  manually where needed.

Committed via a GitHub action: https://github.com/Automattic/jetpack/actions/runs/11056555596

Upstream-Ref: Automattic/jetpack@cc8772d

.github/workflows/wp-svn-autopublish.yml

@@ -31,6 +31,9 @@ jobs:
           fi
           exit $EXIT
 
+      - name: Install svn
+        run: command -v svn || sudo apt-get install -y subversion
+
       - uses: actions/checkout@v4
         with:
           path: src