Cleanup and make sure CI passes (#1)

* normalize composer

* Enable Roave BC check

* Fixed PHPStan

* Remove checks not needed

* cs

* update deps versions

* Fixed lowest build

Author: Nyholm

.github/workflows/checks.yml

@@ -15,11 +15,12 @@
         "psr/http-factory": "^1.0"
     },
     "require-dev": {
-        "symfony/http-client": "^5.0",
         "nyholm/psr7": "^1.2",
         "php-http/discovery": "^1.7",
+        "php-http/httplug": "^2.0",
         "php-http/mock-client": "^1.3",
-        "phpunit/phpunit": "^8.5"
+        "phpunit/phpunit": "^8.5",
+        "symfony/http-client": "^5.0"
     },
     "autoload": {
         "psr-4": {