Allow installation on PHP 8.0 systems

Author: JeroenDeDauw

composer.json

@@ -27,7 +27,7 @@
 		"irc": "irc://irc.freenode.net/wikidata"
 	},
 	"require": {
-		"php": "^7.1",
+		"php": "^8.0|^7.1",
 		"data-values/data-values": "~0.1|~1.0|~2.0",
 		"wikimedia/assert": "~0.2.2|~0.3.0|~0.4.0|~0.5.0"
 	},