Add PrivateAssets=All to Nullable dependency 😅

Author: nblumhardt

src/Serilog.Sinks.File/Serilog.Sinks.File.csproj

@@ -29,7 +29,7 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All" />
     <PackageReference Include="Serilog" Version="2.10.0" />
-    <PackageReference Include="Nullable" Version="1.3.0" />
+    <PackageReference Include="Nullable" Version="1.3.0" PrivateAssets="All" />
   </ItemGroup>
 
   <PropertyGroup Condition=" '$(TargetFramework)' == 'net45' ">