Pin setuptools to < 29 because of AppVeyor failures
Pin setuptools to < 29 because of AppVeyor failures

Related to pypa/setuptools#861

Remove the pin when we have a new setuptools release

rmfitzpatrick/pytest,tgoodlet/pytest,RonnyPfannschmidt/pytest,alfredodeza/pytest,davidszotten/pytest,pfctdayelise/pytest,txomon/pytest,Akasurde/pytest,jaraco/pytest,The-Compiler/pytest,tareqalayan/pytest,hackebrot/pytest,tomviner/pytest,etataurov/pytest,vmalloc/dessert,The-Compiler/pytest,eli-b/pytest,skylarjhdownes/pytest,pytest-dev/pytest,tomviner/pytest,ddboline/pytest,MichaelAquilina/pytest,nicoddemus/pytest,flub/pytest,markshao/pytest,malinoff/pytest,nicoddemus/pytest