module: update go.mod

Author: zchee

go.mod

@@ -1,7 +1,5 @@
 module github.com/go-language-server/jsonrpc2
 
-go 1.12
-
 require (
 	github.com/francoispqt/gojay v1.2.11-0.20190329162224-e46791d21b5e
 	github.com/google/go-cmp v0.3.0
@@ -10,5 +8,5 @@ require (
 	go.uber.org/atomic v1.4.0
 	go.uber.org/multierr v1.1.1-0.20190429210458-bd075f90b08f // indirect
 	go.uber.org/zap v1.10.1-0.20190430155229-8a2ee5670ced
-	golang.org/x/xerrors v0.0.0-20190506180316-385005612d73
+	golang.org/x/xerrors v0.0.0-20190212162355-a5947ffaace3
 )