[Fall fest]: update event image

[techtolentino]

Feature description

Currently, the Qiskit Fall Fest 2023 image is cropping in a not-so-ideal way.

We have a new image that would likely frame nicer than the current one.

Please use this new image: fall-fest-2023.png

Additional context

CC: 👀 @gracelindsell

[techtolentino]

Closed via https://github.com/Qiskit/qiskit.org/pull/3539