CI: Remove 'check_release'-CI-job and 'check_release.py'

This CI-job is a reminder to publish a tag,
when there is no tag for the current version-number.

This does not work well when the version-number is increased
after a release, because there will be no such tag,
until the next release has been published.

Part-of: <https://gitlab.gnome.org/World/Phosh/squeekboard/-/merge_requests/701>

debian/check_release.py

@@ -1,11 +0,0 @@
-#!/usr/bin/env python3
-
-"""Checks tag before release.
-Feed it the first changelog line, and then all available tags.
-"""
-
-import re, sys
-version = re.findall("\\((.*)\\)", input())[0]
-tag = 'v' + re.findall("([0-9]+\\.[0-9]+\\.[0-9]+).*", version)[0]
-if tag not in map(str.strip, sys.stdin.readlines()):
-    raise Exception("Changelog's current version doesn't have a tag. Push the tag!")