Correct last index position

[tiendo1011]

Inside replace_next_larger method, the last_index is calculated as follow: last_index ||= enum.size.
However, semantically, that is the last index in the array plus 1, so I think it should be last_index ||= enum.size - 1

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This change is 

[halostatue]

Reviewed 1 of 1 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @tiendo1011)

[halostatue]

This change looks good. Can you rebase against current master so we can get a clean bill of health from CI?

[tiendo1011]

@halostatue sure, some checks in master are failing so I'll rebase after they pass, is it ok?

[halostatue]

There are some "expected" failures with jruby-head. They should all pass otherwise.

[tiendo1011]

@halostatue I see, I've rebased against master