## Which issue does this PR close?

- Part of #25758.

## Rationale for this change

Prepare the 55.2.0 patch release.

## What changes are included in this PR?

Bumps the version to 55.2.0 in `Cargo.toml`, `Cargo.lock` and the docs,
and adds `dev/changelog/55.2.0.md`.

## What is the testing strategy for this PR?

No code changes. The changelog comes from
`dev/release/generate-changelog.py`.

## Are there any user-facing changes?

No.