Update forum.less to fix the misalignment of the choose tags button

[iamdarkle]

Fixes #0000

Changes proposed in this pull request:

This little PR is simply to remove a CSS rule.

I'm not sure of the reason for this vertical-align: 2px; (maybe at some point you had a good reason), but currently this makes the button display misaligned with respect to the Discussion Title input (although in this case it can go unnoticed), but in conjunction with other extensions it's quite noticeable as it's the only misaligned button, as you can see in the case of the screenshot with flamarkt/taxonomies

Reviewers should focus on:

Is there any need to keep the vertical-align: 2px;?

Screenshots

Current with vertical-align: 2px;

Without vertical-align: 2px; (This PR)

To add other extensions with which the issue is clearly visible:

• fof/polls
• fof/discussion-language

Necessity

• Has the problem that is being solved here been clearly explained?
• If applicable, have various options for solving this problem been considered?
• For core PRs, does this need to be in core, or could it be in an extension?
• Are we willing to maintain this for years / potentially forever?

Confirmed

• Frontend changes: tested on a local Flarum installation.
• Backend changes: tests are green (run composer test).
• Core developer confirmed locally this works as intended.
• Tests have been added, or are not appropriate here.

[askvortsov1]

Less code and less bugs? Sounds like a win to me