fix: keep the workflow token off gist requests

The GITHUB_TOKEN of a workflow is an integration token, and the gists
API answers 403 to those, so every gist plugin failed the install link
check. Gist requests now go out unauthenticated; everything else on
api.github.com still carries the token.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

Author: feildmaster

scripts/plugins.js

@@ -170,7 +170,7 @@ export async function check(text, { network = true } = {}) {
 
 function authenticate(token) {
   axios.interceptors.request.use((config) => {
-    if (config.url?.startsWith('https://api.github.com/')) {
+    if (config.url?.startsWith('https://api.github.com/') && !config.url.startsWith('https://api.github.com/gists/')) {
       config.headers.Authorization = `Bearer ${token}`;
     }
     return config;