[bugfix] Disable Docker builds on AppVeyor Windows platforms
[bugfix] Disable Docker builds on AppVeyor Windows platforms

lcahlander/exist,adamretter/exist,adamretter/exist,windauer/exist,dizzzz/exist,lcahlander/exist,eXist-db/exist,eXist-db/exist,wolfgangmm/exist,wolfgangmm/exist,wolfgangmm/exist,adamretter/exist,dizzzz/exist,ambs/exist,wolfgangmm/exist,adamretter/exist,ambs/exist,lcahlander/exist,lcahlander/exist,dizzzz/exist,wolfgangmm/exist,windauer/exist,wolfgangmm/exist,lcahlander/exist,ambs/exist,ambs/exist,windauer/exist,windauer/exist,eXist-db/exist,windauer/exist,eXist-db/exist,eXist-db/exist,adamretter/exist,lcahlander/exist,adamretter/exist,ambs/exist,ambs/exist,eXist-db/exist,windauer/exist,dizzzz/exist,dizzzz/exist,dizzzz/exist