all: change module to google.golang.org/protobuf

Temporarily remove go.mod, since we can't generate an accurate one until
the corresponding v1 change is submitted.

Change-Id: I1e1ad97f2b455e33f61ffaeb8676289795e47e72
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/177000
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
diff --git a/internal/impl/message.go b/internal/impl/message.go
index a98e7bb..96efec9 100644
--- a/internal/impl/message.go
+++ b/internal/impl/message.go
@@ -11,9 +11,9 @@
 	"strings"
 	"sync"
 
-	pvalue "github.com/golang/protobuf/v2/internal/value"
-	pref "github.com/golang/protobuf/v2/reflect/protoreflect"
-	piface "github.com/golang/protobuf/v2/runtime/protoiface"
+	pvalue "google.golang.org/protobuf/internal/value"
+	pref "google.golang.org/protobuf/reflect/protoreflect"
+	piface "google.golang.org/protobuf/runtime/protoiface"
 )
 
 // MessageType provides protobuf related functionality for a given Go type