Add changelog for 438
This MR was automatically created from CI, https://gitlab.com/gitlab-org/gitter/gitter-android-app/-/jobs/490258586
We copied CURRENT_VERSION.txt
-> 438.txt
This MR was automatically created from CI, https://gitlab.com/gitlab-org/gitter/gitter-android-app/-/jobs/490258586
We copied CURRENT_VERSION.txt
-> 438.txt