Change spelling from converBranch=>convertBranch

Fixed func namespace of `convertBranch` webhook in the gitlab driver.

scm/driver/gitlab/webhook.go

@@ -188,7 +188,7 @@ func convertPushHook(src *pushHook) *scm.PushHook {
 	return dst
 }
 
-func converBranchHook(src *pushHook) *scm.BranchHook {
+func convertBranchHook(src *pushHook) *scm.BranchHook {
 	action := scm.ActionCreate
 	commit := src.After
 	if src.After == "0000000000000000000000000000000000000000" {