Update dependency chai to v4.3.0

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This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
chai (source)	4.2.0 -> 4.3.0

By merging this PR, the below issues will be automatically resolved and closed:

Severity	CVSS Score	CVE	GitHub Issue
High	7.2	CVE-2020-7751	#257

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