fix: specify bash shell for Windows builds in release workflow

🔧 Add explicit shell: bash to Build Binary step
- Fixes Windows runner shell syntax error with [[ ]] syntax
- Ensures consistent bash behavior across all platforms

Resolves Windows build failure in release workflow.

Author: shuaiyang5

.github/workflows/release.yml

@@ -58,6 +58,7 @@ jobs:
           GOOS: ${{ matrix.goos }}
           GOARCH: ${{ matrix.goarch }}
           CGO_ENABLED: 0
+        shell: bash
         run: |
           echo "🔨 Building agentbridge for ${{ matrix.goos }}/${{ matrix.goarch }}..."