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/export.go b/internal/impl/export.go
index 0b53d78..ae0e9fa 100644
--- a/internal/impl/export.go
+++ b/internal/impl/export.go
@@ -8,8 +8,8 @@
 	"reflect"
 	"strconv"
 
-	"github.com/golang/protobuf/v2/encoding/textpb"
-	pref "github.com/golang/protobuf/v2/reflect/protoreflect"
+	"google.golang.org/protobuf/encoding/textpb"
+	pref "google.golang.org/protobuf/reflect/protoreflect"
 )
 
 // Export is a zero-length named type that exists only to export a set of