fix warning about media key in tests (#3048)

Co-authored-by: Wyatt Johnson <wyattjoh@gmail.com>
Co-authored-by: Kim Gardner <kgardnr@gmail.com>

src/core/client/admin/test/fixtures.ts

@@ -645,6 +645,7 @@ export const baseComment = createFixture<GQLComment>({
   ],
   canModerate: true,
   revision: {
+    media: undefined,
     actionCounts: {
       flag: {
         reasons: {