cloudevents v6.0.0

⚠ BREAKING CHANGES

• add http transport and remove axios (#481)

Features

• add http transport and remove axios (#481) (0362a4f)
• precompile cloudevent schema (#471) (b13bde9)

Miscellaneous

• add an npm test:once script (#480) (b4d7aa9)
• update package.json format and deps (#479) (6204805)
• update the release documentation (#476) (c420da4)

Documentation

• update readme to include http builtin transport (#483) (4ab6356)