Bump gui from 6954336 to b28ab16

Bumps [gui](https://github.com/openevse/openevse_wifi_gui) from `6954336` to `b28ab16`.
- [Release notes](https://github.com/openevse/openevse_wifi_gui/releases)
- [Commits](OpenEVSE/openevse_wifi_gui@6954336...b28ab16)

---
updated-dependencies:
- dependency-name: gui
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]