Fix missing fields in mock /room_keys/version responses (#34273)

These mock responses are incomplete, and as of
https://github.com/matrix-org/matrix-js-sdk/pull/5419, will start to fail type
checks.

apps/web/test/unit-tests/components/viewmodels/settings/encryption/KeyStoragePanelViewModel-test.ts

@@ -79,6 +79,8 @@ describe("KeyStoragePanelViewModel", () => {
                 auth_data: {
                     public_key: "foobar",
                 },
+                count: 0,
+                etag: "",
             },
             trustInfo,
         });
@@ -100,6 +102,8 @@ describe("KeyStoragePanelViewModel", () => {
                 auth_data: {
                     public_key: "foobar",
                 },
+                count: 0,
+                etag: "",
             },
             trustInfo: {
                 trusted: false,