Release apertis-dev-tools version 0.2021.4

Signed-off-by: Frédéric Danis <frederic.danis@collabora.com>

debian/changelog

+apertis-dev-tools (0.2021.4) apertis; urgency=medium
+
+  * Add import-debian-package
+  * Add apertis-pkg-{merge,pull}-updates
+  * d/a/local-gitlab-ci.yml: Update apt
+
+ -- Frédéric Danis <frederic.danis@collabora.com>  Mon, 12 Oct 2021 18:03:07 +0200
+
 apertis-dev-tools (0.2021.3) apertis; urgency=medium
 
   * Run the local pipeline whenever the parent pipeline triggers it