Update PHP version requirement to 7.4

Author: donatj

composer.json

@@ -4,7 +4,7 @@
 	"type": "library",
 	"require": {
 		"psr/http-message": "^1 || ^2",
-		"php": ">=7.3"
+		"php": ">=7.4"
 	},
 	"require-dev": {
 		"phpunit/phpunit": "^9.6.19",