update en-GB translation
update en-GB translation

Change-Id: Ic6f4e3a7eb83b6f8986edd19944adf7fe851bd0e
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/300598
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