Move onto the 0.5.x line

Providers, CORS, rate limiting, validation and a command line came with this round, uploaded
files are objects rather than the array PHP wrote them into, and there is a cache and an
event dispatcher to build on, so the stack takes a coordinated step together and asks for
`^0.5` of its own packages.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ARqBYLxrHqevcVmxHkpJcZ

Author: Radoslaw Ziemniewicz

composer.json

@@ -27,11 +27,11 @@
     },
     "require-dev": {
         "phpstan/phpstan": "^2.0",
-        "quillstack/unit-tests": "^0.7"
+        "quillstack/unit-tests": "^0.8"
     },
     "extra": {
         "branch-alias": {
-            "dev-main": "0.4.x-dev"
+            "dev-main": "0.5.x-dev"
         }
     },
     "scripts": {