Stripping all informational serverless messages from rendered yaml file

[maherio]

Context

Rendering the serverless yaml file via sls print can result in a number of informational serverless messages in addition to the actual yaml code - for example, Serverless: Using provider credentials, configured via dashboard...). Rather than hardcode a single message to ignore - Serverless: Running "serverless" installed locally (in service node_modules) - let's ignore all these informational messages in order to only retrieve the rendered yaml itself. This will make this package viable for a wider variety of situations (as well as guard against future changes made to the print output by serverless).

Changeset

• Strips all informational serverless messages

[whisller]

@maherio thank you very much for your contribution! New package will be built shortly :)