Bump ICSharpCode.Decompiler from 7.2.0.6844 to 7.2.1.6856 (#141)

***NO_CI***

Author: dependabot[bot]

source/TestAdapter/nanoFramework.TestAdapter.csproj

@@ -8,7 +8,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="ICSharpCode.Decompiler" Version="7.2.0.6844" />
+    <PackageReference Include="ICSharpCode.Decompiler" Version="7.2.1.6856" />
     <PackageReference Include="Microsoft.TestPlatform.ObjectModel" Version="16.11.0" />
     <PackageReference Include="nanoFramework.nanoCLR.Win32" GeneratePathProperty="true">
       <Version>1.8.0</Version>