update en-GB translation
update en-GB translation

Change-Id: I14b8c3c359a0ea5afa26580fc84e20b9a1909836
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/294322
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>

sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms