Bundling CSS source maps both add unnecessary size, but more importantly cause the css to be served as `blob:`'s.

In more restrictive CSP environments this causes react-devtools-inline to fail to load styles.

Confirmed that the fix works by building locally and using built react-devtools-inline in a restrictive CSP environment. Specifically:
```
styleSrc: 'unsafe-inline' https:
```
where previously the following would be required:
```
styleSrc: 'unsafe-inline' https: blob:
```