The service replies with the message in the request. This can be used as
an attack vector as the reply is determined by the request and is coming
from a shore.co.il domain. So the following precautions are taken:

- Limit the request length to limit the usefulness of the response.
- Set the response MIME type to plain text and set the
  `X-Content-Type-Options` header to `nosniff` so the browser won't
  guess the content type.
- Set the `X-Frame-Options` header to `DENY` so it won't be used as an
  iframe.
- Set CORS headers.

The older version was failing.

- Generate requirementes.txt using pip-compile hook in pre-commit.
- Verify hashes during installation.

Now that the issue was resolved.

For some reason, Docker Compose changed from underscore to hyphen.

With the updated hooks, address some newly found issues:
- Sort Python imports with isort.
- Don't cache pip packages in the container image.

Use the git skeleton file.

Use the renamed CI templates repository.

If the message is an empty string or in the fallback case of using the
request data if the message is None, don't send a notification.

- Remove the manaul stages order, pre-commit now runs in .pre.
- Use a more specific name for building the container image.

There's an issue with version 5.0.0, it requires six but it's missing
from the package requirements. Pin to an older version until it's fixed.

Remove runamel.yaml, json output is available and better.

- Empty service (just the healthcheck).
- Docker image.
- Pre-commit.
- GitLab CI.