Fix packaging slip Error in template file

[alessani]

I'm getting this error while trying to open the packaging slip pdf:

no implicit conversion of Sprockets::Asset into String

This should fix the error.

[tvdeyen]

@alessani thanks. Unfortunately the build fails because filename is no method. Could you please have a look? What Sprockets version are you using locally?

[alessani]

@tvdeyen I'm using sprockets (3.5.2) and sprockets-rails (2.3.3)

[tvdeyen]

The build is using sprockets 2.12.4 and sprocket-rails 2.0.1. So, I guess we need to raise the sprockets version we depend on. It seems that filename was introduced in sprockets 3.3.2, could you please set the dependency accordingly to [">= 3.3.2", "< 4.0"]?

Thanks