try to fix https://ci.appveyor.com/project/grzegorzmazur/yacas/builds/38153292
try to fix https://ci.appveyor.com/project/grzegorzmazur/yacas/builds/38153292

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