ci: add Drone CI

This is my first experiment to make sure I can actually use this in my
CI.

.drone.yml

@@ -0,0 +1,31 @@
+---
+kind: pipeline
+type: exec
+name: Matrix Notifier check
+
+steps:
+- name: Pre-commit checks
+  commands:
+  - nix develop -c pre-commit run --all
+
+- name: Notifiy
+  commands:
+  - nix run .
+  environment:
+    ADDRESS:
+      from_secret: matrix_homeserver
+    ROOM:
+      from_secret: matrix_roomid
+    USER:
+      from_secret: matrix_username
+    PASS:
+      from_secret: matrix_password
+    MESSAGE:
+      # FIXME: need to find a way to link
+      "Build ${DRONE_BUILD_STATUS} [${DRONE_REPO_OWNER}/${DRONE_REPO_NAME}](${dummy_link}) (${DRONE_BRANCH}) by ${DRONE_COMMIT_AUTHOR}"
+  settings:
+    trigger:
+      status:
+        - failure
+        - success
+...