Replace PNPM with NPM in GitHub Actions workflow

.github/actions/install/action.yml

@@ -1,20 +1,13 @@
 name: Install Tools & Dependencies
-description: Installs pnpm, Node.js & package dependencies
+description: Installs Node.js & package dependencies using npm
 
 runs:
   using: composite
   steps:
-    - name: Setup PNPM
-      uses: pnpm/action-setup@v3
-      with:
-        version: 8.15.5
-
     - name: Setup Node
       uses: actions/setup-node@v4
       with:
         node-version: 18
-        cache: pnpm
 
     - name: Install dependencies
-      run: pnpm install
-      shell: bash
+      run: npm install

.github/workflows/ci.yml

@@ -24,10 +24,10 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Install Tools & Dependencies
-        uses: ./.github/actions/install
+        run: npm install
 
       - name: Run Astro Check
-        run: pnpm run check
+        run: npm run check
 
   eslint:
     name: Check for code issues with ESLint
@@ -37,7 +37,7 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Install Tools & Dependencies
-        uses: ./.github/actions/install
+        run: npm install
 
       - name: Run ESLint
-        run: pnpm run lint:eslint
+        run: npm run lint:eslint