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/cmd/conformance/main.go b/internal/cmd/conformance/main.go
index 9f1abb7..6783c16 100644
--- a/internal/cmd/conformance/main.go
+++ b/internal/cmd/conformance/main.go
@@ -12,10 +12,10 @@
 	"log"
 	"os"
 
-	"github.com/golang/protobuf/v2/encoding/jsonpb"
-	"github.com/golang/protobuf/v2/proto"
+	"google.golang.org/protobuf/encoding/jsonpb"
+	"google.golang.org/protobuf/proto"
 
-	pb "github.com/golang/protobuf/v2/internal/testprotos/conformance"
+	pb "google.golang.org/protobuf/internal/testprotos/conformance"
 )
 
 func main() {