Update debug workflow

Author: nekohasekai

.github/workflows/debug.yml

@@ -3,13 +3,15 @@ name: Debug build
 on:
   push:
     branches:
+      - main
       - dev
     paths-ignore:
       - '**.md'
       - '.github/**'
       - '!.github/workflows/debug.yml'
   pull_request:
     branches:
+      - main
       - dev
 
 jobs:
@@ -25,15 +27,6 @@ jobs:
         uses: actions/setup-go@v4
         with:
           go-version: ^1.22
-      - name: Add cache to Go proxy
-        run: |
-          version=`git rev-parse HEAD`
-          mkdir build
-          pushd build
-          go mod init build
-          go get -v github.com/sagernet/sing@$version
-          popd
-        continue-on-error: true
       - name: Build
         run: |
           make test