Add conditional checks for dependency review steps based on event type

Author: borislavr

.github/workflows/dependency-review.yml

@@ -13,13 +13,22 @@ jobs:
         with:
           fetch-depth: 0
       - name: "Get the first commit SHA"
+        if: github.event_name == 'workflow_dispatch'
         id: first-commit
         run: echo "first_commit_sha=$(git rev-list --max-parents=0 HEAD)" >> $GITHUB_ENV
       - name: 'Dependency Review'
+        if: github.event_name == 'workflow_dispatch'
         uses: actions/dependency-review-action@v4
         with:
           base-ref: ${{ env.first_commit_sha }}
           head-ref: ${{ github.ref }}
           show-openssf-scorecard: true
           vulnerability-check: true
           license-check: true
+      - name: 'Dependency Review'
+        if: github.event_name == 'pull_request'
+        uses: actions/dependency-review-action@v4
+        with:
+          show-openssf-scorecard: true
+          vulnerability-check: true
+          license-check: true