Replace gitlab-ci with drone

.drone.yml

@@ -0,0 +1,14 @@
+kind: pipeline
+name: default
+
+platform:
+  os: linux
+  arch: arm
+
+steps:
+- name: check
+  image: silex/emacs:27.2-dev
+  commands:
+  - emacs --version
+  - make ci-dependencies
+  - make check

.gitlab-ci.yml

@@ -1,19 +0,0 @@
-image: ubuntu:latest
-
-.test_job_template: &test_job_definition
-  script:
-    - emacs --version
-    - make ci-dependencies
-    - make check
-
-test:emacs:25.1:
-  image: silex/emacs:25.1-dev
-  <<: *test_job_definition
-
-test:emacs:25.3:
-  image: silex/emacs:25.3-dev
-  <<: *test_job_definition
-
-test:emacs:26:
-  image: silex/emacs:26-dev
-  <<: *test_job_definition