Upgrade @instructure/ui-tree-browser to v7.20.2
Upgrade @instructure/ui-tree-browser to v7.20.2

closes LS-3311
flag = none

Test plan: passes jenkins

Change-Id: I9d556cefd12b309e7123220d2e8ca847730edeb5
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/297413
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
Reviewed-by: Eric Saupe <e7287cf05ae62bc45889f17a9d34b8fae8d5afd1@instructure.com>
QA-Review: Eric Saupe <e7287cf05ae62bc45889f17a9d34b8fae8d5afd1@instructure.com>
Product-Review: Jackson Howe <318c10a818c1b1f2ec50cdcb1827b2c6c5ebd7dc@instructure.com>

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