Update 3.1.0 release date
Update 3.1.0 release date

pfctdayelise/pytest,nicoddemus/pytest,flub/pytest,tareqalayan/pytest,alfredodeza/pytest,tomviner/pytest,The-Compiler/pytest,davidszotten/pytest,MichaelAquilina/pytest,markshao/pytest,tomviner/pytest,rmfitzpatrick/pytest,ddboline/pytest,pytest-dev/pytest,The-Compiler/pytest,RonnyPfannschmidt/pytest,Akasurde/pytest,txomon/pytest,nicoddemus/pytest,hackebrot/pytest