chore: release 6.0.0

[github-actions]

🤖 I have created a release *beep* *boop*

6.0.0 (2022-03-21)

⚠ BREAKING CHANGES

• add http transport and remove axios (feat!: 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)

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This PR was generated with Release Please.

[lance]

@cloudevents/sdk-javascript-maintainers any reason not to land this? I know it's been only about 6 months since the last major version bump, and here we are again. But it would be nice to use the simplified httpTransport in some knative examples. Are there any outstanding fixes or features that folks are hoping to get done before the next release?