Moved guzzle6-adapter out of dev dependencies

Author: bensherred

composer.json

@@ -46,12 +46,12 @@
         "nesbot/carbon": "^2.16",
         "ext-json": "*",
         "php-http/message": "^1.8",
-        "guzzlehttp/psr7": "^1.6"
+        "guzzlehttp/psr7": "^1.6",
+        "php-http/guzzle6-adapter": "^1.0 || ^2.0"
     },
     "require-dev": {
         "phpunit/phpunit": "^8.0 || ^9.0",
         "squizlabs/php_codesniffer": "^3.0",
-        "php-http/guzzle6-adapter": "^1.0 || ^2.0",
         "phpfastcache/phpfastcache": "^7.1"
     },
     "autoload": {