Add support for automated docker builds

Author: DaneEveritt

.github/workflows/docker.yml

@@ -0,0 +1,37 @@
+name: Publish Docker Image
+on:
+  push:
+    branches:
+      - 'develop'
+    tags:
+      - 'v*'
+jobs:
+  push_to_registry:
+    name: Push Image to Github Packages
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: docker/setup-qemu-action@v1
+      - uses: docker/setup-buildx-action@v1
+      - uses: docker/login-action@v1
+        with:
+          registry: ghcr.io
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.REGISTRY_TOKEN }}
+      - name: Release Production Build
+        uses: docker/build-push-action@v2
+        if: contains(github.ref, 'develop') != true
+        env:
+          GITHUB_REF: ${{ github.ref }}
+        with:
+          push: true
+          tags: |
+            ghcr.io/pterodactyl/panel:latest
+            ghcr.io/pterodactyl/panel:${GITHUB_REF}
+      - name: Release Development Build
+        uses: docker/build-push-action@v2
+        if: contains(github.ref, 'develop')
+        with:
+          push: true
+          tags: |
+            ghcr.io/pterodactyl/panel:develop