Bump Microsoft.NET.Test.Sdk from 15.9.0 to 16.3.0 (#125)

Bumps [Microsoft.NET.Test.Sdk](https://github.com/microsoft/vstest) from 15.9.0 to 16.3.0.
- [Release notes](https://github.com/microsoft/vstest/releases)
- [Commits](microsoft/vstest@v15.9.0...v16.3)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

src/common.props

@@ -13,7 +13,7 @@
   <PropertyGroup>
     <XunitVersion>2.4.1</XunitVersion>
     <AkkaVersion>1.3.15</AkkaVersion>
-    <TestSdkVersion>15.9.0</TestSdkVersion>
+    <TestSdkVersion>16.3.0</TestSdkVersion>
     <NetCoreTestVersion>netcoreapp2.1</NetCoreTestVersion>
     <NetFrameworkTestVersion>net461</NetFrameworkTestVersion>
     <NetStandardLibVersion>netstandard1.6</NetStandardLibVersion>