Simple CI file to ensure yarn install works

.github/workflows/node.js.yml

@@ -0,0 +1,30 @@
+# This workflow will do a clean install of node dependencies, build the source code and run tests across different versions of node
+# For more information see: https://help.github.com/actions/language-and-framework-guides/using-nodejs-with-github-actions
+
+# xloem modified this workflow to change npm to yarn, and reduce tests performed
+
+name: Node.js CI
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [10.x, 12.x, 14.x, 15.x]
+        # See supported Node.js release schedule at https://nodejs.org/en/about/releases/
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v1
+      with:
+        node-version: ${{ matrix.node-version }}
+    - run: yarn install

package.json

@@ -24,7 +24,7 @@
     "@stratumn/canonicaljson": "^1.0.2",
     "async": "^2.6.2",
     "debug": "^4.1.1",
-    "epubjs": "^0.3.85",
+    "epubjs": "0.3.87 || ^0.3.89",
     "es2015": "^0.0.0",
     "from2": "^2.3.0",
     "jquery": "^3.3.1",