chore: automate releases with Release-plz (#545)

Releasing the console crates has been a bit of a hassle. It requires
manual work run locally and as such, we have gone long periods without
releases, despite having changes which would be worth releasing.

[Release-plz] provides release automation based on GitHub actions. It
will create, and then update a PR for the next release.

Release-plz depends on [conventional commits] (which the `console`
project is already following) to determine the next version number for
each crate and then uses [cargo-semver-checks] to check that the version
bump is correct.

For the changelogs, [git-cliff] is used. Since we already started using
in #416, so we can reuse our existing `cliff.toml` config file. A small
change has been made to remove the footer, as it was getting included
multiple times in a single changelog file due to the delta updates.

**Caution**: In order to use Release-plz, a crates.io token first needs
to be added to the GitHub project. This means that anyone with PR merge
rights will be able to run a release by merging the Release PR.
Additionally, GitHub actions need to be given permission to create PRs.

The previous scripts used to release have been removed.

[Release-plz]: https://release-plz.ieni.dev/
[conventional commits]: https://www.conventionalcommits.org/en/v1.0.0/
[cargo-semver-checks]: https://github.com/obi1kenobi/cargo-semver-checks
[git-cliff]: https://git-cliff.org/

.github/workflows/release-plz.yml

@@ -0,0 +1,27 @@
+name: Release-plz
+
+permissions:
+  pull-requests: write
+  contents: write
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  release-plz:
+    name: Release-plz
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: Install Rust toolchain
+        uses: dtolnay/rust-toolchain@stable
+      - name: Run release-plz
+        uses: MarcoIeni/release-plz-action@v0.5
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}