Bump versions (#24)

* bump for PHP 8.4 (and beyond)
* bump psr7 version to resolve "Insecure header validation in slim/psr7"

Author: tboronczyk

composer.json

@@ -12,13 +12,13 @@
     }
   ],
   "require": {
-    "php": "^7.2 || ^8.0",
-    "psr/http-message": "^1.0",
-    "psr/http-server-middleware": "^1.0"
+    "php": ">=7.2",
+    "psr/http-message": ">=1.0",
+    "psr/http-server-middleware": ">=1.0"
   },
   "require-dev": {
-    "phpunit/phpunit": "^9.4",
-    "slim/psr7": "^1.0"
+    "phpunit/phpunit": ">=9.4",
+    "slim/psr7": ">=1.4.1"
   },
   "autoload": {
     "psr-4": { "Boronczyk\\": "src/" }