all: replace "pborman/uuid" with "google/uuid"

Internally, "pborman/uuid.NewUUID()" is calling "google/uuid.New()"
that return nil when there is an error [1].

Both package use the same license.

[1] https://github.com/pborman/uuid/blob/master/version1.go#L17

server/mock/mock.go

@@ -4,8 +4,8 @@ import (
 	"errors"
 	"sync"
 
+	"github.com/google/uuid"
 	"github.com/micro/go-micro/server"
-	"github.com/pborman/uuid"
 )
 
 type MockServer struct {
@@ -69,7 +69,7 @@ func (m *MockServer) NewHandler(h interface{}, opts ...server.HandlerOption) ser
 	}
 
 	return &MockHandler{
-		Id:   uuid.NewUUID().String(),
+		Id:   uuid.New().String(),
 		Hdlr: h,
 		Opts: options,
 	}