build: Updating mediawiki/mediawiki-phan-config to 0.9.0

Additional changes:
* Added .eslintcache to .gitignore.

Change-Id: I9c9736c1399422d2668d5a18712cb9b023149ef8

composer.json

@@ -29,7 +29,7 @@
 		"mediawiki/mediawiki-codesniffer": "28.0.0",
 		"jakub-onderka/php-console-highlighter": "0.3.2",
 		"mediawiki/minus-x": "0.3.2",
-		"mediawiki/mediawiki-phan-config": "0.8.0"
+		"mediawiki/mediawiki-phan-config": "0.9.0"
 	},
 	"scripts": {
 		"fix": [