ci: update node20

Author: zhiyuanzmj

.github/workflows/unit-test.yml

@@ -17,7 +17,7 @@ jobs:
       - name: Set node
         uses: actions/setup-node@v3
         with:
-          node-version: 18.x
+          node-version: 20.x
 
       - name: Setup
         run: npm i -g @antfu/ni