chore(ci): don't fail fast for build job

[rwaskiewicz]

Pull request checklist

Please check if your PR fulfills the following requirements:

• Docs have been reviewed and added / updated if needed (for bug fixes / features)
• Build (npm run build) was run locally and any changes were pushed
• Tests (npm test) were run locally and passed
• Prettier (npm run prettier) was run locally and passed

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

If one CI job fails, others may be cancelled without running to completion

GitHub Issue Number: N/A

What is the new behavior?

this commit prevents the build job from failing fast (i.e. if '2' in the
stencil_version matrix fails, the rest of the jobs will not fail). this
ought to allow us to root our stencil version-based errors more easily
if an error pertains to a single version

Does this introduce a breaking change?

• Yes
• No

Testing

ddeeb46 was temporarily added to this branch to add a little bit of chaos/random error throwing. No jobs were cancelled as a result of errors being thrown

Other information