gitattributes: Ensure various media files never get newline-converted.
gitattributes: Ensure various media files never get newline-converted.

This isn't likely, but would happen if their contents happened to look
like a text file to Git's autodetection heuristic.

vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile