remove caching, fixes #176

[peterstadler]

The caching was blocking further requests for different HTTP methods. So, once an e.g. OPTIONS request was cached with a 404, subsequent calls to the same endpoint but via GET where hitting the 404 as well

[daniel-jettka]

this did the trick 👍

[peterprovaznik]

I have noticed that two other <dispatch> elements in data/controller.xql already had the <cache-control cache="no"/>, which makes me more confident that this is a good idea. :)
I have also had a look at eXist docs (https://exist-db.org/exist/apps/doc/urlrewrite#controller-xml) where it says that this caching concerns URL rewriting, which would explain why the HTTP method does not seem to be taken into account.