Allow composer/installers plugin

`composer update --no-interaction` errors out if this flag is not set.
Setting it to true, as that was the status quo before Composer 2.2.

Bug: T298283
Change-Id: I2b14466e51cf1cac89872a9c43ad362561961db2

composer.json

@@ -42,5 +42,10 @@
 		],
 		"phan": "phan -d . --long-progress-bar",
 		"phpcs": "phpcs -sp --cache"
+	},
+	"config": {
+		"allow-plugins": {
+			"composer/installers": true
+		}
 	}
 }