Drop support for python 3.6 and 3.7 in build process

Author: pgarrison

.github/workflows/publish.yml

@@ -13,7 +13,7 @@ jobs:
     - name: Set up Python
       uses: actions/setup-python@v1
       with:
-        python-version: 3.7
+        python-version: 3.8
     - name: Install Dependencies
       run: |
         python -m pip install --upgrade pip

.github/workflows/test-and-lint.yml

@@ -7,7 +7,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        python-version: [3.6, 3.7, 3.8]
+        python-version: [3.8]
         os: [ubuntu-latest, windows-latest, macOS-latest]
 
     steps:
@@ -29,10 +29,10 @@ jobs:
 
     steps:
     - uses: actions/checkout@v1
-    - name: Set up Python 3.7
+    - name: Set up Python 3.8
       uses: actions/setup-python@v1
       with:
-        python-version: 3.7
+        python-version: 3.8
     - name: Install Dependencies
       run: |
         python -m pip install --upgrade pip