[Bug]: mason `publish` missing link to create a PR

[jeremiah-corrado]

The mason publish command should provide the user with a github URL to create a pull request against the mason package registry. See the "publish steps" section in these docs: https://chapel-lang.org/docs/tools/mason/guide/submitting.html

In testing this, I'm seeing that no URL is provided, and the user gets the following output:

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Go to the above link to open up a Pull Request to the mason-registry

It is still possible to create the pull request manually from the user's fork of the mason registry.