Merge pull request #75 from php-http/require-factory-implementation

we need a psr http factory implementation

Author: dbu

composer.json

@@ -21,7 +21,7 @@
         "php-http/httplug": "^2.0",
         "php-http/message": "^1.2",
         "psr/http-client": "^1.0",
-        "psr/http-factory": "^1.0",
+        "psr/http-factory-implementation": "^1.0",
         "symfony/options-resolver": "^3.4 || ^4.0 || ^5.0 || ^6.0"
     },
     "require-dev": {