fix https://ci.appveyor.com/project/grzegorzmazur/yacas/build/1.0.283
fix https://ci.appveyor.com/project/grzegorzmazur/yacas/build/1.0.283

grzegorzmazur/yacas,grzegorzmazur/yacas,grzegorzmazur/yacas,grzegorzmazur/yacas,grzegorzmazur/yacas,grzegorzmazur/yacas,grzegorzmazur/yacas