fix(RepoPage): only show root patches

patches with a 'root' 't' tag according to nip34 draft spec

src/lib/stores/PRs.ts

@@ -53,6 +53,7 @@ export const ensurePRSummaries = async (repo_id: string) => {
         '#a': repo.maintainers.map(
           (m) => `${repo_kind}:${m.hexpubkey}:${repo.repo_id}`
         ),
+        '#t': ['root'],
         limit: 50,
       },
     ],