Support Apple Silicon locally, and test there's no regression

.github/workflows/test.yml

@@ -0,0 +1,25 @@
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+
+jobs:
+  test-build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - run: docker build .
+  test-usage:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./
+        with:
+          input_path: README.md
+          output_dir: generated
+          build_html: false
+      - uses: actions/upload-artifact@v4
+        with:
+          name: readme
+          path: generated

Dockerfile

@@ -1,4 +1,4 @@
-FROM node:18
+FROM --platform=linux/amd64 node:18
 
 RUN wget -q -O - https://dl-ssl.google.com/linux/linux_signing_key.pub | apt-key add - && \
     sh -c 'echo "deb [arch=amd64] http://dl.google.com/linux/chrome/deb/ stable main" >> /etc/apt/sources.list.d/google.list' && \
@@ -24,4 +24,4 @@ RUN fc-cache -fv && \
     chmod 777 /pdf && \
     ln -s /github_interface.js /usr/local/bin/markdown-to-pdf
 
-CMD [ "markdown-to-pdf" ]
+CMD [ "markdown-to-pdf" ]