chore: Release v6

chore: Release v5.4.0

chore: Release v5.3.1

chore: Release v5.3.0

chore: Release v5.2.2

chore: Release v5.2.1

chore: Release v5.2.0

Corrections before point release.

- Fold in fixes to gitignore from serverless#596
- Correct some version numbers in test files.

Version 5.1.0

Changes:
- Removes compatibility with pre-release `poetry`. (Minor version bump.)
- Bump `werkzeug` version to address security issue.
- Correct word splitting on `pip` commands.
- circle CI is working again; much thanks to @miketheman

Known risks:
- Windows CI is still down

SFE support when using package:individually