Update dependencies

Author: davidlis

composer.json

@@ -1,22 +1,22 @@
 {	
-	"name": "sightengine/client-php",
+  "name": "sightengine/client-php",
   "description": "Sightengine PHP client",
   "homepage": "https://sightengine.com",
   "authors": [
     { "name": "Sightengine Team", "homepage": "https://sightengine.com" }
   ],
 
   "require-dev": {
-      "phpunit/phpunit": "^5.7"
+      "phpunit/phpunit": "^9.0"
   },
 
   "require": {
-      "guzzlehttp/guzzle": "~6.0"
+      "guzzlehttp/guzzle": "~7.4"
   },
 
   "autoload": {
     "psr-4": {
       "Sightengine\\": "src/"
     }
   }
-}
+}