[landing] remove react-text-loop dependency

Summary:
In D7911 we removed usage of react-text-loop in our app. This dependency is now no longer used in the project, so I figured it would be good to remove it from our package dependency list

Adding @ashoat as a reviewer since this is a dependency diff

Depends on D7911

Test Plan: N/A for this diff just ran yarn remove react-text-loop in the landing directory

Reviewers: atul, kamil, ashoat

Reviewed By: ashoat

Subscribers: ashoat, tomek, atul

Differential Revision: https://phab.comm.dev/D7914