ci(eol): update workflow from template

Signed-off-by: Richard Steinmetz <richard@steinmetz.cloud>

.github/workflows/block-merge-eol.yml

@@ -2,6 +2,9 @@
 #
 # https://github.com/nextcloud/.github
 # https://docs.github.com/en/actions/learn-github-actions/sharing-workflows-with-your-organization
+#
+# SPDX-FileCopyrightText: 2022-2024 Nextcloud GmbH and Nextcloud contributors
+# SPDX-License-Identifier: MIT
 
 name: Block merges for EOL
 
@@ -23,15 +26,15 @@ jobs:
     runs-on: ubuntu-latest-low
 
     steps:
-      - name: Download updater config
-        run: curl https://raw.githubusercontent.com/nextcloud/updater_server/production/config/config.php --output config.php
-
       - name: Set server major version environment
         run: |
           # retrieve version number from branch reference
           server_major=$(echo "${{ github.base_ref }}" | sed -En 's/stable//p')
           echo "server_major=$server_major" >> $GITHUB_ENV
+          echo "current_month=$(date +%Y-%m)" >> $GITHUB_ENV
 
       - name: Checking if ${{ env.server_major }} is EOL
         run: |
-          php -r 'echo json_encode(require_once "config.php");' | jq --arg version "${{ env.server_major }}" '.stable[$version]["100"].eol // .beta[$version]["100"].eol // "NotEOL"' | grep -q "NotEOL"
+          curl -s https://raw.githubusercontent.com/nextcloud-releases/updater_server/production/config/major_versions.json \
+            | jq '.["${{ env.server_major }}"]["eol"] // "9999-99" | . >= "${{ env.current_month }}"' \
+            | grep -q true