CSS: Fix line-height property value in timer.css
Summary:
`line-height: auto;` is an invalid property value per Syntax definition on https://developer.mozilla.org/en-US/docs/Web/CSS/line-height.
Use the correct value two lines lower (which gets picked up anyway).
Test Plan: Likely show an MFA timer dialog that you have to wait before reusing your code. But I did not test this.
Reviewers: O1 Blessed Committers, mainframe98
Reviewed By: O1 Blessed Committers, mainframe98
Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno
Differential Revision: https://we.phorge.it/D26466