Update date format in workflow and remove delete step

.github/workflows/build.yml

@@ -22,7 +22,8 @@ jobs:
         run: sing-box rule-set compile --output subnets.srs subnets.json
       - name: Set up variables
         id: vars
-        run: echo "date_now=$(date +"%Y_%m_%d_%H_%M_%S")" >> "${GITHUB_OUTPUT}"
+        run: |
+          echo "date_now=$(date +"%Y-%m-%d %T")" >> "${GITHUB_OUTPUT}"
       - name: Upload files to Releases
         uses: ncipollo/release-action@v1
         with:
@@ -36,10 +37,3 @@ jobs:
           name: Updatable rule sets
           removeArtifacts: true
           tag: updatable-rule-sets
-      - name: Delete older releases
-        uses: dev-drprasad/delete-older-releases@v0.3.4
-        with:
-          keep_latest: 1
-          delete_tags: true
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}