Update to run with cocotb 1.72

[davekeeshan]

Hi There

I was looking at this code, and while it was working, there were a few updates required to make it play with the most up to date version of cocotb (1.7.2). I had a little fiddliness getting my actions working first.

• Change cocotb.fork (which is being deprecated) to cocotb.start_soon
• Update actions revs (checkout@v3, setup-python@v4)
• Add Python 3.10
• Remove Python 3.6
• Update README example code (send -> write ; recv -> read)

[davekeeshan]

bump

Reviewing old pull request, this is still outstanding, this merge request should go through, python 3.12 could be added too