ci: Revert support for node.js 18 (#4518) (#4537)

Revert "ci: Start supporting node.js 18 (#4518)"

This reverts commit 9ee292cd17.

.github/workflows/ci-postgres-mysql.yml

@@ -15,17 +15,12 @@ jobs:
       DB_MYSQLDB_PASSWORD: password
       DB_POSTGRESDB_PASSWORD: password
 
-    strategy:
-      matrix:
-        node-version: [14.x, 16.x, 18.x]
-
     steps:
       - uses: actions/checkout@v3
 
-      - name: Use Node.js ${{ matrix.node-version }}
-        uses: actions/setup-node@v3
+      - uses: actions/setup-node@v3
         with:
-          node-version: ${{ matrix.node-version }}
+          node-version: 16.x
           cache: 'npm'
 
       - name: Install npm and dependencies