feat(ci): add mergify configuration (#172)

* feat(ci): add mergify configuration

* meta: add work-in-progress label
* fix: restrict build and docker workflows to main

.github/labels.yml

@@ -64,3 +64,6 @@
 - name: wontfix
   description: This will not be worked on
   color: ffffff
+- name: work-in-progress
+  description: Work in progress that should not be auto-merged
+  color: ffffff

.github/mergify.yml

@@ -0,0 +1,20 @@
+pull_request_rules:
+  - name: self-assign PRs
+    conditions:
+      - -merged
+      - -closed
+      - "#assignee=0"
+    actions:
+      assign:
+        add_users:
+          - "{{ author }}"
+  - name: automatic merge for main when CI passes and 2 reviews and not WIP
+    conditions:
+      - "#approved-reviews-by>=1"
+      - check-success=test
+      - check-success=build-and-push-image
+      - base=main
+      - label!=work-in-progress
+    actions:
+      merge:
+        method: squash

.github/workflows/build.yml

@@ -3,6 +3,8 @@ name: Build
 on:
   workflow_dispatch:
   push:
+    branches:
+      - main
   pull_request:
 
 jobs:

.github/workflows/docker.yml

@@ -3,6 +3,8 @@ name: Docker
 on:
   workflow_dispatch:
   push:
+    branches:
+      - main
   pull_request:
 
 env: