This way we actually detect problems like
https://github.com/element-hq/synapse/pull/19475 as they happen instead
of being invisible until something breaks.
Sanity check that Complement is testing against your code changes
(whether it be local or from the PR in CI).
```
COMPLEMENT_DIR=../complement ./scripts-dev/complement.sh --in-repo -run TestSynapseVersion
```
