ci: don't install webpack again (webpack-contrib#1440)

Author: ersachin3112

.github/workflows/nodejs.yml

@@ -75,6 +75,7 @@ jobs:
         run: npm ci
 
       - name: Install webpack ${{ matrix.webpack-version }}
+        if: matrix.webpack-version != 'latest'
         run: npm i webpack@${{ matrix.webpack-version }}
 
       - name: Run tests for webpack version ${{ matrix.webpack-version }}