fix: fix multi item mode in ai:ask command

[mwwoda]

According to spec https://developer.box.com/reference/post-ai-ask/#param-mode the correct name for mode is multiple_item_qa instead of multi_item_qa

[mwwoda]

Coveralls failing, needs to be investigated

[coveralls]

Pull Request Test Coverage Report for Build 18038301699

Details

• 3 of 3 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.04%) to 85.542%

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Totals
Change from base Build 16808319744:	0.04%
Covered Lines:	4593
Relevant Lines:	5179

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💛 - Coveralls