build: run on node 18 on pr only (#5)

Author: iBotPeaches

.github/workflows/ci.yml

@@ -3,14 +3,13 @@ on:
   pull_request:
     branches:
       - master
-  push:
 
 jobs:
   build:
     runs-on: ubuntu-22.04
     strategy:
       matrix:
-        node: ['16', '18']
+        node: ['18']
     name: Node ${{ matrix.node }}
     steps:
       - uses: actions/checkout@v3