backward compatible to older versions of tramp (2.6.x)

[dasoju]

Hi
Can you please remove the restriction of tramp "2.8.0.5"

I am on mac and use mitsuharu emacs which is currently at emacs29 which uses tramp 2.6.x.
Once i use tramp-hlo I am forced to move to 2.8.0.5 and this is breaking other packages that use tramp, for example dired-subtree

Thanks !

[jsadusk]

I'm currently using features that are only in recent tramp releases. Specifically tramp-add-external-operation which was added in tramp 2.8. I could try and write a backward compatibility mode to work without it, but its not trivial.