Bump version: 5.1.1 → 5.2

Bump version: 5.1 → 5.1.1

Bump version: 5.0.0.2 → 5.1

Manually fix errors made by bump2version.

See c4urself/bump2version#182.

Fixed the download url probably being different.

[code_generator] Bump a version v5.0.b4 -> v5.0.0.

Bump version to v5.0b4.

Bump version to v5.0b3.

So pip calls it `5.0.0b1` instead of `5.0.0-beta.1`, so I'll re-relea…

…se it as `5.0.0b2` just to have a clear version.

Cut a `5.0.0-beta.1` release.