update en-GB translation
update en-GB translation

Change-Id: I82d9f27ad8517ace5d87514c73e1e8bc6e4a7707
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/270447
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