ci: keep up with mysql driver updates

[detule]

We should probably think about how we can avoid needing to do this in the future.

Couple of options:

• We can ask choco to install a fixed version, I believe; or
• Extract the driver version programmatically and inject it into the connection string.

First one is easy; the second would allow us to move forward with the driver versions without upkeep.

[detule]

Ended up going with the latter.

[simonpcouch]

Perfect. Thanks for making this happen.