Remove use of deprecated autoload feature

gsherwood · gsherwood · commit 1a2dcf78ab4f · 2021-01-14T15:23:03.000+11:00
diff --git a/phpstan.neon b/phpstan.neon
@@ -2,7 +2,7 @@ parameters:
     level: 0
     paths:
         - src
-    autoload_files:
+    bootstrapFiles:
         - tests/bootstrap.php
     ignoreErrors:
         -
