Suppress warnings when matching go packages with devel version

[wagoodman]

Today when you are matching against a golang package with a devel version, you see this warning:

[0000]  WARN could not match by package language (package=Pkg(type=go-module, name=./staging/src/k8s.io/api, version=(devel), upstreams=0)): matcher failed to parse version pkg="./staging/src/k8s.io/api" ver="(devel)": Malformed version: (devel)

However, this case is quite common, and there is nothing the user can do about this so we should not be showing this warning.

This PR makes the following changes:

• an explicit error case that other version constructors can use in the future
• changes this to a trace log