labels: remove hacktoberfest-accepted

I think we should not (as an org) encourage participation.

Individual tracks can decide differently a year from now when
Hacktoberfest rolls around again.

exercism/org-wide-files#266

.github/labels.yml

@@ -157,11 +157,6 @@
   description: "Work on Documentation"
   color: "ffffff"
 
-# This label can be added to accept PRs as part of Hacktoberfest
-- name: "hacktoberfest-accepted"
-  description: "Make this PR count for hacktoberfest"
-  color: "ff7518"
-
 # This Exercism-wide label is added to all automatically created pull requests that help migrate/prepare a track for Exercism v3
 - name: "v3-migration 🤖"
   description: "Preparing for Exercism v3"