compose: Slightly move send button upwards.
compose: Slightly move send button upwards.

This may have got misaligned after my last minutes changes to
the compose refactor PR.

kou/zulip,rht/zulip,kou/zulip,zulip/zulip,kou/zulip,kou/zulip,zulip/zulip,rht/zulip,andersk/zulip,andersk/zulip,kou/zulip,andersk/zulip,andersk/zulip,eeshangarg/zulip,zulip/zulip,rht/zulip,rht/zulip,eeshangarg/zulip,eeshangarg/zulip,zulip/zulip,eeshangarg/zulip,andersk/zulip,zulip/zulip,kou/zulip,zulip/zulip,rht/zulip,kou/zulip,rht/zulip,eeshangarg/zulip,andersk/zulip,eeshangarg/zulip,andersk/zulip,rht/zulip,zulip/zulip,eeshangarg/zulip