ci: Install Eask

Author: jcs090218

.github/workflows/main.yml

@@ -38,7 +38,12 @@ jobs:
       with:
         version: ${{ matrix.emacs-version }}
 
+    - uses: emacs-eask/setup-eask@master
+      with:
+        version: 'snapshot'
+
     - uses: actions/checkout@v2
+
     - name: Run tests
       run: |
         eask install-deps