fix: syntax error of runs-on (chaos-mesh#4576)

Author: g1eny0ung

.github/workflows/integration_test.yml

@@ -36,7 +36,7 @@ jobs:
       fail-fast: false
       matrix:
         arch: [amd64, arm64]
-    runs-on: ${{ fromJson('{"amd64":"ubuntu-20.04", "arm64":"github-arm64-2c-8gb"]}')[matrix.arch] }}
+    runs-on: ${{ fromJson('{"amd64":"ubuntu-20.04", "arm64":"github-arm64-2c-8gb"}')[matrix.arch] }}
     steps:
       - uses: actions/checkout@v4
         with: