.github: Support testing multiple architectures
.github: Support testing multiple architectures

Now that this is supported by actions/setup-node, make it easy for
projects using this template to test on multiple architectures.

Signed-off-by: Kevin Locke <ffb4761cba839470133bee36aeb139f58d7dbaa9@kevinlocke.name>

kevinoid/promised-read,kevinoid/git-branch-is,kevinoid/swagger-spec-validator,kevinoid/stream-compare,kevinoid/node-project-template,kevinoid/promised-read,kevinoid/node-project-template,kevinoid/git-branch-is,kevinoid/promised-read,kevinoid/travis-status,kevinoid/appveyor-status,kevinoid/swagger-spec-validator,kevinoid/appveyor-status,kevinoid/travis-status,kevinoid/appveyor-status,kevinoid/git-branch-is,kevinoid/swagger-spec-validator,kevinoid/stream-compare,kevinoid/node-project-template,kevinoid/stream-compare,kevinoid/travis-status