Update Zulip tests and re-enable (#441)

This has the update to unblock autocomplete changes:
  zulip/zulip-flutter#1190
  flutter/flutter#143249

and with that, tests pass again on Flutter main.

Also install libsqlite3-dev on Linux, a package which is no longer
included in GitHub's new version of the "ubuntu-latest" images.  The
lack of it causes nondeterministic failures when the runner happens
to use the new image:
  #441 (comment)

The actual shared library file libsqlite3.so.0.8.6 -- in the package
libsqlite3-0 -- is still installed by default anyway.  This package
adds the symlink at "libsqlite3.so", which is the filename some
libraries apparently look for.

registry/zulip.test.disabled → registry/zulip.test

@@ -2,7 +2,9 @@ contact=greg@zulip.com
 contact=cbobbe@zulip.com
 
 fetch=git clone https://github.com/zulip/zulip-flutter.git tests
-fetch=git -C tests checkout 28b3536bc81b6665a6014ce72f40c51f83b0c5c4
+fetch=git -C tests checkout 0bfa79d23fc9fcf5ce0cc5a21540434f526838d9
+
+setup.linux=sudo apt install -y libsqlite3-dev
 
 update=.
 update=packages/zulip_plugin