ci: Change github UID from 3434 to 1001.
ci: Change github UID from 3434 to 1001.

CircleCI expected 3434; GitHub Actions expects 1001.  This is the
reason zulip-ci.yml currently needs to mess with the permissions in
/__w.

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

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