Added types, min PHP version is now 8.0

Author: cseufert

composer.json

@@ -28,13 +28,13 @@
     "source": "https://github.com/cseufert/hamle"
   },
   "require": {
-    "php": ">=7.4.0",
+    "php": ">=8.0",
     "psr/log": "~1.0",
     "ext-mbstring": "*"
   },
   "require-dev": {
     "phpunit/phpunit": ">= 8.5",
-    "vimeo/psalm": "^4.7"
+    "vimeo/psalm": "^4.18"
   },
   "autoload": {
     "psr-4": {