shared: Add missing katex dependency to shared package.json.
shared: Add missing katex dependency to shared package.json.

Signed-off-by: Anders Kaseorg <dfdb7392591db597bc41cf266a9c3bc12a2706e5@zulip.com>

rht/zulip,andersk/zulip,eeshangarg/zulip,showell/zulip,eeshangarg/zulip,zulip/zulip,rht/zulip,kou/zulip,zulip/zulip,showell/zulip,kou/zulip,eeshangarg/zulip,punchagan/zulip,eeshangarg/zulip,kou/zulip,rht/zulip,brainwane/zulip,punchagan/zulip,brainwane/zulip,brainwane/zulip,kou/zulip,eeshangarg/zulip,andersk/zulip,brainwane/zulip,andersk/zulip,showell/zulip,punchagan/zulip,brainwane/zulip,zulip/zulip,andersk/zulip,punchagan/zulip,zulip/zulip,showell/zulip,hackerkid/zulip,hackerkid/zulip,showell/zulip,hackerkid/zulip,rht/zulip,showell/zulip,hackerkid/zulip,andersk/zulip,punchagan/zulip,brainwane/zulip,rht/zulip,eeshangarg/zulip,hackerkid/zulip,andersk/zulip,eeshangarg/zulip,punchagan/zulip,kou/zulip,showell/zulip,zulip/zulip,andersk/zulip,kou/zulip,zulip/zulip,zulip/zulip,hackerkid/zulip,kou/zulip,punchagan/zulip,rht/zulip,brainwane/zulip,hackerkid/zulip,rht/zulip