Support for previewing changelog

--preview is different to --check in that it outputs in the CHANGELOG.md format
Also fixes the CHANGELOG.md changelog consolidation

Automate publishing to npm

v1.2.0

Create release.yml

Fix the ignoring of comments to work when more than one comment is present

Merge pull request #35 from matrix-org/t3chguy-patch-1

Apply global flag to comment regexes

Ignore keywords which are commented out

Merge pull request #34 from matrix-org/t3chguy/ignore-comments

Ignore commands in the comments

Ability to require a T- label to be set

Using inputs.requireLabel: true