Merge pull request #219 from LSSTDESC/u/yymao/update-action

Update python action

.github/workflows/pythonpackage.yml

@@ -1,6 +1,10 @@
 name: Python package
 
-on: [push, pull_request]
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
 
 jobs:
   build:
@@ -9,19 +13,19 @@ jobs:
     strategy:
       max-parallel: 4
       matrix:
-        python-version: [3.7]
+        python-version: [3.7, 3.8]
 
     steps:
     - uses: actions/checkout@v2
     - name: Cache Python packages
-      uses: actions/cache@v1
+      uses: actions/cache@v2
       with:
         path: ~/.cache/pip
         key: ${{ runner.os }}-py${{ matrix.python-version }}-pip-${{ hashFiles('setup.py') }}
         restore-keys: |
           ${{ runner.os }}-py${{ matrix.python-version }}-pip-
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v1
+      uses: actions/setup-python@v2
       with:
         python-version: ${{ matrix.python-version }}
     - name: Install gfortran  # required by camb
@@ -31,6 +35,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
+        pip install wheel
         pip install .[full]
     - name: Lint with flake8
       run: |