Release Workflow: Install Subversion (WordPress#68837)

Co-authored-by: Mamaduka <mamaduka@git.wordpress.org>
Co-authored-by: joemcgill <joemcgill@git.wordpress.org>
Co-authored-by: desrosj <desrosj@git.wordpress.org>

.github/workflows/upload-release-to-plugin-repo.yml

@@ -167,6 +167,10 @@ jobs:
             VERSION: ${{ github.event.release.name }}
 
         steps:
+            - name: Install Subversion
+              run: |
+                  apt-get update -y && apt-get install -y subversion
+
             - name: Check out Gutenberg trunk from WP.org plugin repo
               run: |
                   svn checkout "$PLUGIN_REPO_URL/trunk" --username "$SVN_USERNAME" --password "$SVN_PASSWORD"
@@ -222,6 +226,10 @@ jobs:
             VERSION: ${{ github.event.release.name }}
 
         steps:
+            - name: Install Subversion
+              run: |
+                  apt-get update -y && apt-get install -y subversion
+
             - name: Download and unzip Gutenberg plugin asset into tags folder
               env:
                   PLUGIN_URL: ${{ github.event.release.assets[0].browser_download_url }}