soketto 0.8.0

A websocket protocol implementation.
Documentation
# Release Checklist

These steps assume that you've checked out the Soketto repository and are in the root directory of it.

We also assume that ongoing work done is being merged directly to the `master` branch.

1.  Ensure that everything you'd like to see released is on the `master` branch.

2.  Create a release branch off `master`, for example `release-v0.6.0`. The branch name should start with `release`
    so that we can target commits with CI. Decide how far the version needs to be bumped based on the changes to date.
    If unsure what to bump the version to (e.g. is it a major, minor or patch release), check with the Parity Tools team.

3.  Check that you're happy with the current documentation.

    ```
    cargo doc --open --all-features
    ```

    CI checks for broken internal links at the moment. Optionally you can also confirm that any external links
    are still valid like so:

    ```
    cargo install cargo-deadlinks
    cargo deadlinks --check-http -- --all-features
    ```

    If there are minor issues with the documentation, they can be fixed in the release branch.

4.  Bump the crate version in `Cargo.toml` to whatever was decided in step 2.

5.  Update `CHANGELOG.md` to reflect the difference between this release and last. If you're unsure of
    what to add, check with the Tools team.

    One way to gain some inspiration on what to write is to look at the [closed PRs]https://github.com/paritytech/soketto/pulls?q=is%3Apr+is%3Aclosed.

    You can also look through the commit history to find the code changes since the last release (eg `git log --pretty LAST_VERSION_TAG..HEAD`).

6.  Commit any of the above changes to the release branch and open a PR in GitHub with a base of `master`.

7.  Once the branch has been reviewed and passes CI, merge it.

8.  Now, we're ready to publish the release to crates.io.

    Checkout `master`, ensuring we're looking at that latest merge (`git pull`).

    Next, do a dry run to make sure that things seem sane:
    ```
    cargo publish --dry-run
    ```

    If we're happy with everything, proceed with the release:
    ```
    cargo publish
    ```

9.  If the release was successful, then tag the commit that we released in the `master` branch with the
    version that we just released, for example:

    ```
    git tag v0.6.0 # use the version number you've just published to crates.io, not this one
    git push --tags
    ```

    Once this is pushed, go along to [the releases page on GitHub]https://github.com/paritytech/soketto/releases
    and draft a new release which points to the tag you just pushed to `master` above. Copy the changelog comments
    for the current release into the release description.