feat: update ci

Author: dacongda

.github/workflows/ci.yml

@@ -15,7 +15,7 @@ jobs:
         with:
           go-version: 1.24
 
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v2
       - name: Run Unit tests
         run: go test -v ./...
 
@@ -24,7 +24,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
 
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v2
       - name: Run semantic-release
         if: github.repository == 'casdoor/notify2' && github.event_name == 'push'
         run: |