Change release branch to testing, and bump mac and windows action to Python 3.9

.github/workflows/test_mac.yml

@@ -1,10 +1,10 @@
-name: macOS (3.8)
+name: macOS (3.9)
 
 on:
   push:
-    branches: [ main, dev, release ]
+    branches: [ main, testing, dev ]
   pull_request:
-    branches: [ main, dev, release ]
+    branches: [ main, testing, dev ]
 
 jobs:
   testMac38:
@@ -13,7 +13,7 @@ jobs:
       - name: Python Setup
         uses: actions/setup-python@v2
         with:
-          python-version: 3.8
+          python-version: 3.9
           architecture: x64
       - name: Install Packages
         run: |