Bump elliptic from 6.4.1 to 6.5.3 in /packages/mst-example-bookshop (#1558)
Bump elliptic from 6.4.1 to 6.5.3 in /packages/mst-example-bookshop (#1558)

[skip ci]
mweststrate/mobx-state-tree,mweststrate/mobx-state-tree,mobxjs/mobx-state-tree,mobxjs/mobx-state-tree,mobxjs/mobx-state-tree,mobxjs/mobx-state-tree