Update Node versions

Author: daffl

.github/workflows/test-matrix.yml

@@ -12,7 +12,7 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [18, 20]
+        node-version: [22]
         elasticsearch-version: ['8.15.0', '9.0.0']
 
     name: Node ${{ matrix.node-version }} - ES ${{ matrix.elasticsearch-version }}