Boolean Select from Material UI theme can never be set to Yes/true

[davidnyman-caci]

Prerequisites

• I have read the documentation;
• In the case of a bug report, I understand that providing a SSCCE example is tremendously useful to the maintainers.
• Ideally, I'm providing a sample JSFiddle or a shared playground link demonstrating the issue.

Description

When using the Material UI theme, the select drop down will always display a value of "No", all change events show the formData has a value of false for the field, regardless of what was selected. This appears to be an issue with the @rjsf/material-ui library, the provided example works as expected when using the default theme.

This seems to be caused by https://github.com/rjsf-team/react-jsonschema-form/blob/master/packages/material-ui/src/SelectWidget/SelectWidget.tsx#L25 where it fails a strict equality check of the value; the function is given a boolean true or false, which is never equal to "true". It appears the same problem was encountered by https://github.com/rjsf-team/react-jsonschema-form/blob/master/packages/semantic-ui/src/SelectWidget/SelectWidget.js#L44

Steps to Reproduce

1. Go to the playground https://rjsf-team.github.io/react-jsonschema-form/
2. Change the theme from default to material-ui
3. Paste the following text into the JSONSchema field

{
  "type": "object",
  "properties": {
    "myStuckBoolean": {
      "type": "boolean",
      "title": "myStuckBoolean"
    }
  }
}

4. Paste the following text into the UISchema field

{
  "myStuckBoolean": {
    "ui:widget": "select"
  }
}

5. Paste the following text into the formData field

{
  "myStuckBoolean": true
}

6. Select "Yes" on the generated form

Expected behavior

Selecting Yes causes it to be selected/reselected

Actual behavior

No is always selected/reselected regardless of choice

Version

"@rjsf/core@2.4.2",
"@rjsf/material-ui@2.4.2",

[heath-freenome]

This was fixed in the v5 beta