Install

1. Install package control for Sublime Text 3.
2. Add this repository: (Ctrl + Shift + P + Add repo + https://github.com/vors/sublime-powershell-v5)
3. Install package sublime-powershell-v5 (Ctrl + Shift + P + install + powershell-v5)

Choose syntax

Now you can choose syntax "Powershell v5". If you have original "Powershell v2" package, it will be kept as default for .ps1, psm1, psd1 files. You may want to remove previous package.