Remove git ref text

Remove the git text refs/tags/ from the ReleaseVersion input to only access the tag number (and suffix).
This will allow this to be used within the Github Actions with the parameter {{ github.ref }} when run on tags: trigger

Fix entrypoint to full path

Fixing the entrypoint of the Docker image to the full path to the compiled binary /app/OctoClient
This is to allow this image to work within the Github Actions environment where they override
the workdir on run.

Add Channel Input

Add channel input and package to release

The previous version did not include the package version when building a release
This change pulls in the template in order to set the package version for the
release that is created. The channel name is needed in order to get the proper
deployment template, so the additional input was added as optional. The channel
defaults to 'Default' as created by Octopus Deploy