Update the Pico Display examples to use ST7789.
Since LED and Button input was also part of the Pico Display modules, replace with pimoroni.Button and pimoroni.RGBLED.
* Display temp as 00.00 with floating point component
* Use the temp value to blend from a list of display colours
* Fixed slowdown bug when screen begins to scroll
Keep the bouncing balls in the court and gives balls a speed in proportion to their size. Created from code in #63
Co-authored-by: Mark Emery <mark@markemerylimited.co.uk>