Fix tmux panic (#165)

Fix `tmux` sessions

This will create a new session named `topgrade`, `topgrade-1`,
`topgrade-2`, using the first nonexistent session name it finds. That
session will have a window in it named `topgrade` in which `topgrade` is
run. If `topgrade --tmux` is being run from within tmux, it won't attach
to the new tmux session. If the user is not currently in tmux, it will
attach to the newly-created session.

Co-authored-by: Thomas Schönauer <37108907+DottoDev@users.noreply.github.com>

src/steps/remote/ssh.rs

@@ -26,7 +26,7 @@ pub fn ssh_step(ctx: &ExecutionContext, hostname: &str) -> Result<()> {
         #[cfg(unix)]
         {
             prepare_async_ssh_command(&mut args);
-            crate::tmux::run_command(ctx, &shell_words::join(args))?;
+            crate::tmux::run_command(ctx, hostname, &shell_words::join(args))?;
             Err(SkipStep(String::from("Remote Topgrade launched in Tmux")).into())
         }