From `proyects` to `projects`.

Upgrade self-test hook from v1.23.0 to v2.24.0. The former version
crashes with the following error:

ImportError: cannot import name 'soft_unicode' from 'markupsafe'

Configure Commitizen to automatically bump the version of its own hook
that it uses.

Use the new location of the repository in the commitizen-tools org.

The existing regex had numerous bugs and boiled down to a very complex
way of matching any file whatsoever in the tests directory. Correct the
syntax issues, and make a best guess at the original intent.

Replace "script" with the current name of the directory, "scripts."

The original explanation has some minor grammatical errors.

- Specify what output_lines and lines are lists of, namely strings.
- Remove unnecessary test of whether latest_version_position is an int since
  x != None for any integer x.
- Replace two consecutive list.append calls with a single list.extend call.

Ensure there is at least one blank line separating old and new content.
We already separate the log entries for each release with blank lines,
so separate pre-existing content from the first release with a blank
line as well. If the pre-existing content ends in a blank line, then
don't add an extra one.

Ensure At Least One Blank Line Between Old and New Changelog Content