prevent `package.json` version from being out of sync when not updated as part of release

[travi]

if a project has a version set in package.json, but does not configure the release to update that version as part of the release, set the version to 0.0.0-semantically-released instead.

this could be because the project does not define a custom release config, or defines one but does not include the git plugin, or the npm plugin, do does not include package.json in the assets list for the git plugin.