Added support for Node 20

ref https://linear.app/tryghost/issue/ENG-765/add-support-for-node-20

- this adds support for Node 20 because it is EOL and is suitable for
  our support policy

.github/workflows/test.yml

@@ -11,7 +11,7 @@ jobs:
     if: github.event_name == 'push' || (github.event_name == 'pull_request' && !startsWith(github.head_ref, 'renovate/'))
     strategy:
       matrix:
-        node: [ '16.13.0', '18.12.1' ]
+        node: [ '16.13.0', '18.12.1', '20.11.1' ]
         env:
           - DB: sqlite3
             NODE_ENV: testing

package.json

@@ -44,7 +44,7 @@
     "knex-migrator-rollback": "./bin/knex-migrator-rollback"
   },
   "engines": {
-    "node": "^14.18.0 || ^16.13.0 || ^18.12.1"
+    "node": "^14.18.0 || ^16.13.0 || ^18.12.1 || ^20.11.1"
   },
   "dependencies": {
     "@tryghost/database-info": "0.3.21",