Update to PSR-7 2.0

Author: ralflang

.horde.yml

@@ -38,7 +38,7 @@ dependencies:
       horde/exception: ^3
       horde/util: ^3
       horde/support: ^3
-      psr/http-message: ^1
+      psr/http-message: ^2
   dev:
     composer:
       horde/test: ^3

composer.json

@@ -28,7 +28,7 @@
         "horde/exception": "^3 || dev-FRAMEWORK_6_0",
         "horde/util": "^3 || dev-FRAMEWORK_6_0",
         "horde/support": "^3 || dev-FRAMEWORK_6_0",
-        "psr/http-message": "^1"
+        "psr/http-message": "^2"
     },
     "require-dev": {
         "horde/test": "^3 || dev-FRAMEWORK_6_0",