feat(express): add support for redirectProxyUrl (#9657)

* fix: Github provider tests

* feat: add support for redirectProxy to framework-express

Author: ndom91

packages/frameworks-express/src/index.ts

@@ -164,6 +164,7 @@ export function ExpressAuth(
 ): ReturnType<typeof ExpressAuthHandler> {
   const { ...authOptions } = config
   authOptions.secret ??= process.env.AUTH_SECRET
+  authOptions.redirectProxyUrl ??= process.env.AUTH_REDIRECT_PROXY_URL
   authOptions.trustHost ??= !!(
     process.env.AUTH_TRUST_HOST ??
     process.env.VERCEL ??