Add uploading artifacts to CI

Author: lixin9311

.github/workflows/build.yml

@@ -25,7 +25,16 @@ jobs:
         fi
 
     - name: Build
-      run: go build -v .
+      run: |
+        mkdir build
+        go build -o go-shadowsocks2 -v . && zip ./build/go-shadowsocks2_linux-x64.zip go-shadowsocks2
+        GOOS=darwin go build -o go-shadowsocks2 -v . && zip ./build/go-shadowsocks2_darwin-x64.zip go-shadowsocks2
+        GOOS=windows go build -o go-shadowsocks2.exe && zip ./build/go-shadowsocks2_win-x64.zip go-shadowsocks2.exe
+
+    - name: Upload artifacts
+      with:
+        name: artifacts
+        path: ./build
 
     - name: Test
       run: |