Update MacOS_CI.yml (AtsushiSakai#507)

* Update MacOS_CI.yml

* Update MacOS_CI.yml

* Update MacOS_CI.yml

* Update MacOS_CI.yml

* Update MacOS_CI.yml

Author: AtsushiSakai

.github/workflows/MacOS_CI.yml

@@ -8,7 +8,7 @@ on: [push, pull_request]
 
 jobs:
   build:
-    runs-on: ubuntu-latest
+    runs-on: macos-latest
     strategy:
       matrix:
         python-version: [ '3.9' ]
@@ -17,6 +17,9 @@ jobs:
       - uses: actions/checkout@v2
       - run: git fetch --prune --unshallow
 
+      - name: Update bash
+        run: brew install bash
+
       - name: Setup python
         uses: actions/setup-python@v2
         with:
@@ -25,6 +28,7 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
+          pip install numpy # cvxpy install workaround
           pip install -r requirements.txt
       - name: install coverage
         run: pip install coverage