Ignore Nuget package directory name casing

It looks like VS2017 changed it's nuget package directory name to be capitalized.
When using Ubuntu for Windows, directory name casing of NuGet package folder becomes important and detected as a change by git,. This change is to ignore regardless of casing.

VisualStudio.gitignore

@@ -171,11 +171,11 @@ PublishScripts/
 # NuGet Packages
 *.nupkg
 # The packages folder can be ignored because of Package Restore
-**/packages/*
+**/[Pp]ackages/*
 # except build/, which is used as an MSBuild target.
-!**/packages/build/
+!**/[Pp]ackages/build/
 # Uncomment if necessary however generally it will be regenerated when needed
-#!**/packages/repositories.config
+#!**/[Pp]ackages/repositories.config
 # NuGet v3's project.json files produces more ignorable files
 *.nuget.props
 *.nuget.targets