Fix CI test environment (#391)

Co-authored-by: Brent Bumann <bbumann@dropbox.com>

Author: Brent1LT

.github/workflows/ci.yml

@@ -11,13 +11,13 @@ jobs:
     strategy:
       matrix:
         os: [macos-latest, windows-latest]
-        python-version: [2.7, 3.5, 3.6, 3.7, 3.8, pypy2, pypy3]
+        python-version: [2.7, 3.5, 3.6, 3.7, 3.8, pypy-2.7, pypy-3.7]
         exclude:
           - os: windows-latest
             python-version: 3.6
         include:
-          - os: linux
-            python-version: 3.4
+          - os: ubuntu-latest
+            python-version: 3.7
     steps:
       - uses: actions/checkout@v2
       - name: Setup Python environment
@@ -65,13 +65,13 @@ jobs:
     strategy:
       matrix:
           os: [macos-latest, windows-latest]
-          python-version: [2.7, 3.5, 3.6, 3.7, 3.8, pypy2, pypy3]
+          python-version: [2.7, 3.5, 3.6, 3.7, 3.8, pypy-2.7, pypy-3.7]
           exclude:
             - os: windows-latest
               python-version: 3.6
           include:
-            - os: linux
-              python-version: 3.4
+            - os: ubuntu-latest
+              python-version: 3.7
     steps: 
       - uses: actions/checkout@v2.3.4
       - name: Setup Python environment