[BUGFIX] Width of action column is wrong

The width of the action column in the workspaces module is
wrong. 5 icons with a width of 16px each need to be displayed
and results in a required width of 80px.

Fixes: #50210
Releases: 6.0, 6.1, 6.2
Change-Id: I3e1cbfd9be53c57dad86a6003edbf38b559dab73
Reviewed-on: https://review.typo3.org/22453
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters