stylelint: Fix keyframes-name-pattern.
stylelint: Fix keyframes-name-pattern.

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

zulip/zulip-desktop,zulip/zulip-desktop,zulip/zulip-desktop,zulip/zulip-desktop