fix: extmarks missing from final line

[jradam]

I noticed that while extmarks are present on the first line (<<<<<<< HEAD), they are missing from the final line of the incoming changes (>>>>>>> new_branch), so I extended them to include it.

<<<<<<< HEAD (Current changes)
-- Code
=======
-- Code
>>>>>>> new_branch (Incoming changes)
-- There were no extmarks on this ^^ line

Merging this would help with selecting conflicts by extmark.

[akinsho]

Thanks @jradam 🙏🏾

[jradam]

Awesome, thanks @akinsho!