Upgrade Guzzle Promises Function API to Static API

Guzzle Promises:
A static API was first introduced in 1.4.0, in order to mitigate problems with functions conflicting between global and local copies of the package. The function API was removed in 2.0.0.

https://github.com/guzzle/promises#upgrading-from-function-api

src/Ganesha/GuzzleMiddleware.php

@@ -46,7 +46,7 @@ public function __invoke(callable $handler): \Closure
             $serviceName = $this->serviceNameExtractor->extract($request, $options);
 
             if (!$this->ganesha->isAvailable($serviceName)) {
-                return \GuzzleHttp\Promise\rejection_for(
+                return \GuzzleHttp\Promise\Create::rejectionFor(
                     new RejectedException(
                         sprintf('"%s" is not available', $serviceName)
                     )
@@ -62,11 +62,11 @@ function ($value) use ($serviceName) {
                     } else {
                         $this->ganesha->success($serviceName);
                     }
-                    return \GuzzleHttp\Promise\promise_for($value);
+                    return \GuzzleHttp\Promise\Create::promiseFor($value);
                 },
                 function ($reason) use ($serviceName) {
                     $this->ganesha->failure($serviceName);
-                    return \GuzzleHttp\Promise\rejection_for($reason);
+                    return \GuzzleHttp\Promise\Create::rejectionFor($reason);
                 }
             );
         };