Add Mergify config

.github/mergify.yml

@@ -0,0 +1,50 @@
+pull_request_rules:
+  - name: Automatic merge
+    conditions:
+      - "#approved-reviews-by>=1"
+      - label=automerge
+      - status-success=Lint
+      - status-success=continuous-integration/appveyor/pr
+      - status-success=continuous-integration/travis-ci/pr
+
+      # Test
+      - status-success=macOS-latest Python 3.6
+      - status-success=macOS-latest Python 3.7
+      - status-success=macOS-latest Python 3.8
+      - status-success=macOS-latest Python 3.9-dev
+      - status-success=macOS-latest Python pypy3
+      - status-success=ubuntu-latest Python 3.6
+      - status-success=ubuntu-latest Python 3.7
+      - status-success=ubuntu-latest Python 3.8
+      - status-success=ubuntu-latest Python 3.9-dev
+      - status-success=ubuntu-latest Python pypy3
+
+      # Test Docker
+      - status-success=alpine
+      - status-success=amazon-1-amd64
+      - status-success=amazon-2-amd64
+      - status-success=arch
+      - status-success=centos-6-amd64
+      - status-success=centos-7-amd64
+      - status-success=centos-8-amd64
+      - status-success=debian-10-buster-x86
+      - status-success=fedora-31-amd64
+      - status-success=fedora-32-amd64
+      - status-success=ubuntu-18.04-bionic-amd64
+      - status-success=ubuntu-20.04-focal-amd64
+
+      # Test Windows
+      - status-success=MSYS2 MinGW 32-bit
+      - status-success=MSYS2 MinGW 64-bit
+      - status-success=Python 3.6 x64
+      - status-success=Python 3.6 x86
+      - status-success=Python 3.7 x64
+      - status-success=Python 3.7 x86
+      - status-success=Python 3.8 x64
+      - status-success=Python 3.8 x86
+      - status-success=Python 3.9-dev x64
+      - status-success=Python 3.9-dev x86
+      - status-success=Python pypy3 x86
+    actions:
+      merge:
+        method: merge