Update dependency react-i18next to v15

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
react-i18next	^14.1.0 -> ^15.0.0

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Release Notes

i18next/react-i18next (react-i18next)

v15.0.1

Compare Source

• revert arrow function in class property to address this

v15.0.0

Compare Source

• use optional chaining, nullish coalescing and nullish coalescing assignment 1774
• Build config and optimizations 1769
• some dependency updates 1768
• use modern hasLoadedNamespace code (now requires at least i18next > v19.4.5 (introduced in june 2020))

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