Add missing platyPS dependency in CI builds

Author: daviwil

appveyor.yml

@@ -18,6 +18,7 @@ install:
   - ps: |
       Install-PackageProvider -Name NuGet -MinimumVersion 2.8.5.201 -Force | Out-Null
       Install-Module InvokeBuild -RequiredVersion 3.2.1 -Scope CurrentUser -Force | Out-Null
+      Install-Module platyPS -RequiredVersion 0.7.6 -Scope CurrentUser -Force | Out-Null
 
 build_script:
   - ps: Invoke-Build

build/travis.ps1

@@ -1,5 +1,6 @@
 # Install InvokeBuild
 Install-Module InvokeBuild -Scope CurrentUser -Force
+Install-Module PlatyPS -Scope CurrentUser -Force
 
 # Build the code and perform tests
 Import-module InvokeBuild