Allow psr/http-message v2 (#364)

Co-authored-by: Dzmitry Chubryk <[email protected]>

Author: FlashBlack

composer.json

@@ -40,7 +40,7 @@
         "php-http/discovery": "^1.4",
         "php-http/httplug": "^1.0 || ^2.0",
         "php-http/message": "^1.7",
-        "psr/http-message": "^1.0"
+        "psr/http-message": "^1.0 || ^2.0"
     },
     "require-dev": {
         "nyholm/psr7": "^1.6.1",