Remove probot-move.

This has been replaced with GitHub's beta feature.

.github/move.yml

-# Configuration for move-issues - https://github.com/dessant/move-issues
-
-# Delete the command comment. Ignored when the comment also contains other content
-deleteCommand: true
-# Close the source issue after moving
-closeSourceIssue: true
-# Lock the source issue after moving
-lockSourceIssue: true
-# Mention issue and comment authors
-mentionAuthors: true
-# Preserve mentions in the issue content
-keepContentMentions: true
-# Set custom aliases for targets
-aliases:
-  core: Homebrew/homebrew-core