Add Dockerfile and container build workflow

.github/workflows/build-container.yaml

@@ -0,0 +1,31 @@
+name: Build Container
+
+"on":
+  push:
+    branches:
+      - main
+    tags:
+      - "v[0-9]+.[0-9]+.[0-9]+"
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+      - name: Login to GHCR
+        uses: docker/login-action@v2
+        if: github.event_name != 'pull_request'
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      - name: Build and push
+        id: docker_build
+        uses: docker/build-push-action@v4
+        with:
+          push: true
+          tags: |
+            ghcr.io/${{ github.repository_owner }}/mastodon_get_replies:${{ github.ref_name }}
+            ghcr.io/${{ github.repository_owner }}/mastodon_get_replies:latest

Dockerfile

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+FROM python:3.11-alpine
+WORKDIR /app
+COPY ./requirements.txt /app/requirements.txt
+RUN pip install --no-cache-dir --upgrade -r /app/requirements.txt
+COPY ./find_posts.py /app/
+ENTRYPOINT ["python", "find_posts.py"]