Style: format code by gofumpt (#761)

common/buf/buffer_test.go

@@ -78,6 +78,7 @@ func TestBufferByte(t *testing.T) {
 		buffer.Release()
 	}
 }
+
 func TestBufferResize(t *testing.T) {
 	buffer := New()
 	defer buffer.Release()

common/buf/io.go

@@ -121,7 +121,7 @@ func NewWriter(writer io.Writer) Writer {
 		return mw
 	}
 
-	var iConn = writer
+	iConn := writer
 	if statConn, ok := writer.(*stat.CounterConnection); ok {
 		iConn = statConn.Connection
 	}