Bug#1067961: python3-sbml5 depends on swig

[Matthias Klose]

Package: python3-sbml5
Version: 5.20.2+dfsg-2.1
Severity: important.
python3-sbml5 has a runtime dependency on swig, which seems to be wrong. 
swig is used to create the bindings at build time.  That pulls in swig 
with all it's dependencies ...