release: Update Cargo.toml and CHANGELOG for 0.6.9 release

[skinsbursky]

Summary of the PR

Create new release

Requirements

Before submitting your PR, please make sure you addressed the following
requirements:

• [ x] All commits in this PR have Signed-Off-By trailers (with
  git commit -s), and the commit message has max 60 characters for the
  summary and max 75 characters for each description line.
• All added/changed functionality has a corresponding unit/integration
  test.
• All added/changed public-facing functionality has entries in the "Upcoming
  Release" section of CHANGELOG.md (if no such section exists, please create one).
• Any newly added unsafe code is properly documented.