Remove deploy-preview workflow which is never used

.github/workflows/deploy-preview.yml

@@ -1,28 +0,0 @@
-name: Deploy preview
-
-on:
-  pull_request_target: null
-
-jobs:
-  deploy:
-    runs-on: ubuntu-24.04
-    continue-on-error: true
-    steps:
-      - name: Checkout code
-        uses: actions/checkout@v6
-        with:
-          repository: ${{ github.event.pull_request.head.repo.full_name }}
-          ref: ${{ github.event.pull_request.head.ref }}
-      - name: Use node.js
-        uses: actions/setup-node@v6
-        with:
-          node-version: 24.14
-      - name: Build
-        run: |
-          npm ci && \
-          node ./scripts/set-homepage.cjs /shlink-web-client/${GITHUB_HEAD_REF#refs/heads/} && \
-          node --run build
-      - name: Deploy preview
-        uses: shlinkio/deploy-preview-action@v1.0.1
-        with:
-          folder: build