chore(deps): update github/issue-metrics action to v4

Author: renovate[bot]

.github/workflows/issue-metrics.yml

@@ -44,7 +44,7 @@ jobs:
           echo "last_month=$first_day..$last_day" >> "$GITHUB_ENV"
 
       - name: Run issue-metrics tool
-        uses: github/issue-metrics@v3
+        uses: github/issue-metrics@v4
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           SEARCH_QUERY: 'spring-boot-admin:codecentric/spring-boot-admin is:issue created:${{ env.last_month }} -reason:"not planned"'