CI: Don’t use Drone CI anymore

.drone.yml

@@ -1,35 +0,0 @@
-kind: pipeline
-name: default
-
-steps:
-- name: fetch
-  image: alpine/git
-  commands:
-  - git fetch --tags
-
-- name: build debian package
-  image: evolix/gbp:bullseye
-  branches:
-  - debian
-  commands:
-  - mk-build-deps --install --remove debian/control
-  - git clean --force
-  - gbp buildpackage -us -uc
-  when:
-    branch:
-    - debian
-
-- name: upload debian package
-  image: drillster/drone-rsync
-  settings:
-    hosts: ["pub.evolix.net"]
-    port: 22
-    user: droneci
-    key:
-      from_secret: drone_private_key
-    target: /home/droneci/bkctld/
-    source: ../bkctld*
-    delete: true
-  when:
-    branch:
-    - debian