Fix detection of secondary rate limit

Actual error message is "You have exceeded a secondary rate limit and have been temporarily blocked from content creation. Please retry your request again later. If you reach out to GitHub Support for help, please include the request ID [...]"

Author: mathieudz

lib/Github/HttpClient/Plugin/GithubExceptionThrower.php

@@ -128,7 +128,7 @@ public function handleRequest(RequestInterface $request, callable $next, callabl
             }
 
             $reset = (int) ResponseMediator::getHeader($response, 'X-RateLimit-Reset');
-            if ((403 === $response->getStatusCode()) && 0 < $reset && isset($content['message']) && (0 === strpos($content['message'], 'You have exceeded a secondary rate limit.'))) {
+            if ((403 === $response->getStatusCode()) && 0 < $reset && isset($content['message']) && (0 === strpos($content['message'], 'You have exceeded a secondary rate limit'))) {
                 $limit = (int) ResponseMediator::getHeader($response, 'X-RateLimit-Limit');
 
                 throw new ApiLimitExceedException($limit, $reset);