build: Updating mediawiki/phan-taint-check-plugin to 1.3.0

And updating CoC link to use Special:MyLanguage (T202047).

Change-Id: I35ff4c638ad70886b8f496e358a64dda78d5c8f1

CODE_OF_CONDUCT.md

@@ -1 +1 @@
-The development of this software is covered by a [Code of Conduct](https://www.mediawiki.org/wiki/Code_of_Conduct).
+The development of this software is covered by a [Code of Conduct](https://www.mediawiki.org/wiki/Special:MyLanguage/Code_of_Conduct).

composer.json

@@ -17,6 +17,6 @@
 		]
 	},
 	"extra": {
-		"phan-taint-check-plugin": "1.2.0"
+		"phan-taint-check-plugin": "1.3.0"
 	}
 }