Change PDB type to portable to avoid VS2019 compile warning

[MagicAndre1981]

Sample

open SearchBarDemos.sln from this project and try to compile it

Description

You get this VS warning about old PDB format

2>C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\MSBuild\Xamarin\Android\Xamarin.Android.Legacy.targets(385,5): warning XA0125: 'SearchBarDemos.pdb' is using a deprecated debug information level.
2>C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\MSBuild\Xamarin\Android\Xamarin.Android.Legacy.targets(385,5): warning XA0125: Set the debugging information to Portable in the Visual Studio project property pages or edit the project file in a text editor and set the 'DebugType' MSBuild property to 'portable' to use the newer, cross-platform debug information level.
2>C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\MSBuild\Xamarin\Android\Xamarin.Android.Legacy.targets(385,5): warning XA0125: If this file comes from a NuGet package, update to a newer version of the NuGet package or notify the library author.

Steps to Reproduce

1. open SearchBarDemos.sln from this project
2. try to compile it
3. look at warning in build output

Expected Behavior

no warning

Actual Behavior

warning about wrong PDB format

Information

• IDE and IDE version: VS2019 16.9.2
• Platform with the issue:
  • iOS:
  • Android: 10.0
  • UWP:
• Device or simulator/emulator: