Legacy context API warning

[mogaozq]

Calendar component triggers this two warnings in React 17.x releases :

First warning

Warning: Legacy context API has been detected within a strict-mode tree.
The old API will be supported in all 16.x releases, but applications using it should migrate to the new version.

Please update the following components: Calendar, Heading

Second warning

Warning: Using UNSAFE_componentWillReceiveProps in strict mode is not recommended and may indicate bugs in your code. See https://reactjs.org/link/unsafe-component-lifecycles for details.

• Move data fetching code or side effects to componentDidUpdate.
• If you're updating state whenever props change, refactor your code to use memoization techniques or move it to static getDerivedStateFromProps. Learn more at: https://reactjs.org/link/derived-state

Please update the following components: Calendar