misc(ci): Add GitHub Actions docker build and publish

.github/workflows/docker-image_publish.yml

@@ -0,0 +1,20 @@
+name: Docker Image Publish
+on:
+  push:
+    branches: ["master"]
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+    environment: DockerHub
+    steps:
+    - uses: actions/checkout@v4
+    - name: Log in to Docker Hub
+      uses: docker/login-action@v3
+      with:
+        username: ${{ secrets.DOCKERHUB_USERNAME }}
+        password: ${{ secrets.DOCKERHUB_TOKEN }}
+    - name: Build and push Docker image
+      uses: docker/build-push-action@v5
+      with:
+        push: true
+        tags: mumblevoip/mumo