Pin System.ComponentModel.Annotations to 4.4.0 (see #277)

Author: Michael Ganss

XmlSchemaClassGenerator/XmlSchemaClassGenerator.csproj

@@ -49,7 +49,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All" />
-    <PackageReference Include="System.ComponentModel.Annotations" Version="5.0.0" />
+    <PackageReference Include="System.ComponentModel.Annotations" Version="[4.4.0]" />
     <PackageReference Include="System.Text.Encoding.CodePages" Version="5.0.0" />
     <PackageReference Include="System.ValueTuple" Version="4.5.0" />
   </ItemGroup>