Add Python 3.9 terminal tests

Author: SkeletalDemise

.github/workflows/terminaltest.yml

@@ -7,7 +7,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: [3.7, 3.8]
+        python-version: [3.7, 3.8, 3.9]
     steps:
     - uses: actions/checkout@v2
     - name: Set up Python ${{ matrix.python-version }}