Simplify relay request headers

src/lib/twitter-client-search.ts

@@ -105,7 +105,7 @@ export function withSearch<TBase extends AbstractConstructor<TwitterClientBase>>
           try {
             const response = await this.fetchWithTimeout(url, {
               method: 'POST',
-              headers: this.getHeaders(),
+              headers: this.getJsonHeaders(),
               body: JSON.stringify({ features, queryId }),
             });