feat: upgrade to react v18

[ripecosta]

Description:

Upgrades to react v18.

Checklist

• only relevant code is changed (make a diff before you submit the PR)
• run tests npm run test
• tests are included
• commit message and code follows the Developer's Certification of Origin

[coveralls]

coverage: 97.073% (-0.02%) from 97.094%
when pulling f4238b0 on ripecosta:rc/react
into 8276a35 on i18next:master.

[adrai]

Theoretically, if we keep the peerDependency of react as is, there is no need for a breaking release, since the v18 react is only needed because of the tests.
I know there are a lot of users still using react 16/17...
I would prefer not to drop this older react compatibility for now.
We can say older versions are not supported, but technically still compatible.
What do you think?

[ripecosta]

@adrai If in the future we use a feature that isn't compatible with v16/17 we could that break compatibility without realising. However since the project is pretty stable (and so is react) I guess that's not very likely to happen. I'm happy to not bump the react version if that's your preference.

Any thoughts on the test with the comment? Leave as is/simplify? I'll make the peerdep change now to unblock this PR from being merged but can simplify the tests in a separate PR if you think that's fine.

[adrai]

ok, 👍
Regarding the test: it is important in that test case that no render is triggered.

[ripecosta]

I see. In that case I'll leave the test as is.

I have reverted the change to the react peer deps so the PR should be ready to merge.

[adrai]

thank you 👍