Should document ispyb-database version requirement

SynchWeb should clearly document which version of [ispyb-database](https://github.com/DiamondLightSource/ispyb-database) it requires (e.g., "ispyb-database 1.20.0 or later"). This should be done in the same way that most programs and libraries document their dependencies. Without this, I'm left guessing and trying things like using the latest from the `master` branch of the SynchWeb and ispyb-database repos, or using snapshots from the SynchWeb and ispyb-database repos that are approximately from the same point in time.