Unijoysticle2 generates noise making a high-pitch sound on the C128

Bug reported by Krzysztof Dabrowski:

When using the Unijoysticle2 in "self powered" mode (when not using external power supply), the ESP32 seems to be generating some noise in the +5V line that conflicts with the C128 (in C128 mode), and generates a high-pitch sound.

This was also reproducible with Kospec's Unijoysticle2 device in Reloaded MK2 and with a regular C64.

The problem seems to be that the ESP32 doesn't have any decoupling capacitor. Adding a high-pass and a low-pass filter capacitors might fix it.

https://www.dropbox.com/s/hhjvekhmpu8d3lc/standard_c64.MOV?dl=0