[BUGFIX] Update @typo3/icons to 3.1.2

The TYPO3 icon set is updated to version 3.1.2 which fixes a regression
with buttons.

See full changelog here:
https://github.com/TYPO3/TYPO3.Icons/compare/v3.1.0...v3.1.2

Executed commands:

    cd Build
    nvm use
    yarn add @typo3/icons@^3.1.2
    grunt build

Resolves: #97872
Resolves: #97842
Releases: main
Change-Id: Iba778452d913defbf34654ec52efa08cd5728f02
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/75049


Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Nikita Hovratov <nikita.h@live.de>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Nikita Hovratov <nikita.h@live.de>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>