chore: upgrade all dev dependencies (#376)

Upgrade available minor and patch versions of all dependencies, and
ESLint v9.
As part of ESLint major upgrade the ESLint config was migrated to flat
config, the plugins and rules used were cleaned up, and minor lint
issues were fixed.

chore: upgrade all dev dependencies (#376)

Upgrade available minor and patch versions of all dependencies, and
ESLint v9.
As part of ESLint major upgrade the ESLint config was migrated to flat
config, the plugins and rules used were cleaned up, and minor lint
issues were fixed.

feat: use @octokit/action instead of @octokit/core (#198)

As mentioned in #194, the current code doesn't support GitHub Enterprise
Server.
This PR fixes that by switching from `@octokit/core` to
`@octokit/action` which uses `baseUrl` from GitHub Action context and
therefore supports GHES out of the box.

feat: upgrade node to v20 (#95)

The node18 runner is not going to be supported by Github, and the
current Node LTS version is 18. So let's jump directly from v16 to v20,
to keep up with Node LTS.

BREAKING CHANGE: The action now runs on node20 runner. If you use
self-hosted runners, make sure you are able to run actions with node
v20.

fix: remove invalid header

fix: remove invalid header

fix: prepare action.yml for GitHub Marketplace (#22)

Change the action name so it's unique and add branding.

fix: remove hardcoded days-to-delete & exit with 0 when no branches f…

…or deletion found

chore: change release workflow node version (#19)

chore(release): 1.0.0 [skip ci]

# 1.0.0 (2023-07-29)

### chore

* bump version ([30294d2](30294d2))

### BREAKING CHANGES

* intial release