Contributing guidelines: Remove references to Travis CI and AppVeyor (#8617)
Contributing guidelines: Remove references to Travis CI and AppVeyor (#8617)

Since when was Travis-CI used??  I removed it and replaced it with `Azure DevOps` because that isn't there.  

PaulHigin/PowerShell,JamesWTruher/PowerShell-1,TravisEz13/PowerShell,PaulHigin/PowerShell,TravisEz13/PowerShell,daxian-dbw/PowerShell,daxian-dbw/PowerShell,daxian-dbw/PowerShell,PaulHigin/PowerShell,TravisEz13/PowerShell,JamesWTruher/PowerShell-1,JamesWTruher/PowerShell-1,TravisEz13/PowerShell,daxian-dbw/PowerShell,JamesWTruher/PowerShell-1,PaulHigin/PowerShell