Mercury

The frontend wasn't packed correctly in the previous release (2.3.5). This release fixes it.

Fixes
- (362) change footer
- (373) update django to 4.2.2

Fixes
- 290 adjust margins in `NumberBox`
- 307 fix URL in share dialog, thanks kapily!

Enhancements
- 263 better error message if notebook not found
- 273 display Mercury version on local server start
- 274 set custom domain for Site in database
- 276 nicer display of output files for download
- 278 allow widgets in the loop
- 290 add `NumberBox` widget

Bug fixes
- 246 fix share button on Safari web browser
- 265 set allowed Python versions 3.8-3.11
- 277 fix show prompt in Safari
- 275 fix private notebook display when stored on S3
- 282 fix output files for download

Fixes
- 252 fix problem with slides navigation after widget update

Fixes
- 253 Django update to version 4.2
- 255, 237 fixes port and server address forwarding issues