Update dependency System.Drawing.Common to v8 (#626)

+semver:patch

Author: renovate[bot]

src/FluentNHibernate.Testing/FluentNHibernate.Testing.csproj

@@ -31,7 +31,7 @@
   </ItemGroup>
 
   <ItemGroup Condition=" '$(TargetFramework)' == 'net6.0' ">
-    <PackageReference Include="System.Drawing.Common" Version="6.0.0" />
+    <PackageReference Include="System.Drawing.Common" Version="8.0.3" />
   </ItemGroup>
 
   <ItemGroup>