Use React API forceUpdate() for forceRenderChildren().

[baerrach]

Patch for #773

Using setState({}) causes unnecessary re-renders as {} is always a new object.

TODO:

• If this PR is a new feature, reference an issue where a consensus about the design was reached (not necessary for small changes)
• Make sure all of the significant new logic is covered by tests
• Rebase your changes on master so that they can be merged easily
• Make sure all tests and linter rules pass
• Update CHANGELOG.md with your change
• If this was a change that affects the external API, update the docs and post a link to the PR in the discussion
• If this was a change that affects GitHunt-React, update GitHunt-React and post a link to the PR in the discussion

[helfer]

LGTM