Docker action gha

Signed-off-by: dada513 <dada513@protonmail.com>

.github/workflows/docker.yml

@@ -0,0 +1,22 @@
+name: ci
+
+on:
+  push:
+    branches:
+      - 'master'
+
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v2
+        with:
+          registry: ghcr.io
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      - name: Build and push
+        uses: docker/build-push-action@v3
+        with:
+          push: true
+          tags: ghcr.io/polymc/bot:latest