Removed direct dependency on cs3apis

As we now use the CS3APIs via the cs3client (#161), this dependency
is not needed any longer.

Author: glpatcern

requirements.txt

@@ -7,7 +7,6 @@ PyJWT
 requests
 more_itertools
 prometheus-flask-exporter
-cs3apis>=0.1.dev101
 waitress
 wheel>=0.38.0 # not directly required, pinned by Snyk to avoid a vulnerability
 setuptools>=70.0.0 # not directly required, pinned by Snyk to avoid a vulnerability