chore: add support for tmux 3.7 - #997

@iyuuya Take a look at PR #927 ; there's an additional file for CI that needs to be updated as well

Thanks, @farzadmf! That CI-file update was the old approach from before #981. #981 reworked CI to use snapshot-based interface tests instead of a tmux version matrix, so new tmux versions no longer need a CI file change — just SUPPORTED_TMUX_VERSIONS + CHANGELOG + spec update, as #989 did for 3.6b. This PR follows that same pattern.

@akofink can we get a release for this? thanks 😄

Thanks, @farzadmf! That CI-file update was the old approach from before #981. #981 reworked CI to use snapshot-based interface tests instead of a tmux version matrix, so new tmux versions no longer need a CI file change — just SUPPORTED_TMUX_VERSIONS + CHANGELOG + spec update, as #989 did for 3.6b. This PR follows that same pattern.

Oh, good to know; thanks for letting me know @iyuuya