Upgrading react-test-renderer 17 to 18

Removes the unstable scheduler/tracing API.

Removes the object-assign polyfill.

Removes the unsupported unstable_changedBits API.

Disallows complex children inside title elements to match browser constraints.

Introduces automatic batching of more state updates, with flushSync available to opt out.

Adds a development-only Strict Mode check that unmounts and remounts every component on first mount, restoring previous state.

Makes useEffect timing consistent by synchronously flushing effect functions when an update is triggered during a discrete input event.

Treats hydration mismatches from missing or extra text content as errors and reverts to client rendering up to the closest Suspense boundary.

Keeps Suspense trees consistent by discarding an incomplete tree when a component suspends before being fully added, then retrying rendering from scratch.

Layout effects are now cleaned up when a tree re-suspends and re-created when the boundary content is shown again.

Throws when act is used in production.

Warns for deprecated findDOMNode outside StrictMode.

Warns for deprecated test-utils methods.

Warns for deprecated Legacy Context outside StrictMode.

Warns for deprecated string refs outside StrictMode.

Warns for deprecated defaultProps for function components.

Warns when using act from test-utils.

Warns for deprecated unmountComponentAtNode.

Warns for deprecated renderToStaticNodeStream.

Discourages the existing renderToString method, which keeps working.

Deprecates ReactDOM.render, which now warns and runs the app in React 17 mode.

Deprecates ReactDOM.unmountComponentAtNode.

Deprecates ReactDOM.renderSubtreeIntoContainer.

Deprecates ReactDOMServer.renderToNodeStream.

Warns if renderSubtreeIntoContainer is called.

Deprecates renderToNodeStream.