Update 'psr/http-message' allowed version to ^2.0

Author: Mike van der Velde

composer.json

@@ -36,7 +36,7 @@
         "psr/http-client-implementation": "^1.0",
         "psr/http-factory": "^1.0",
         "psr/http-factory-implementation": "^1.0",
-        "psr/http-message": "^1.0",
+        "psr/http-message": "^1.0 || ^2.0",
         "psr/http-message-implementation": "^1.0",
         "psr/http-server-middleware": "^1.0",
         "web-token/jwt-checker": "^2.0 || ^3.0",