NuGet update with packages.config doesn't consider targets files

[brettfo]

Found in a package update in the wild, a .csproj/packages.config project (net462 TFM) had a dependency on System.Text.Json version 6.0.6 and a line in the project file looked like this:

...
<Import Project="..\packages\System.Text.Json.6.0.6\build\System.Text.Json.targets" Condition="Exists('..\packages\System.Text.Json.6.0.6\build\System.Text.Json.targets')" />
...

After updating System.Text.Json to 8.0.1, that path was expected to be updated to:

..\packages\System.Text.Json.8.0.1\buildTransitive\net462\System.Text.Json.targets"