Hashtags of all digits should not link

Hashtags which are all digits (e.g., #1 (closed)) should not link. This behavior is consistent with twitter.

mentioned in merge request !4 (closed)

Closed the MR as @egor had a better solution.

Is the suggested regex matching Mastodon's behavior acceptable, @lanodan ?

mentioned in merge request !5 (merged)

closed via commit 8e9de09c

closed via merge request !5 (merged)