#98 drop supporting python 3.6/3.7

.github/workflows/pythonpackage.yml

@@ -9,7 +9,7 @@ jobs:
     strategy:
       max-parallel: 4
       matrix:
-        python-version: [3.6, 3.7, 3.8]
+        python-version: [3.8]
 
     steps:
       - uses: actions/checkout@v1

.github/workflows/pythonpublish.yml

@@ -12,7 +12,7 @@ jobs:
     - name: Set up Python
       uses: actions/setup-python@v1
       with:
-        python-version: '3.6'
+        python-version: '3.8'
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip

.github/workflows/weekly_test.yml

@@ -11,7 +11,7 @@ jobs:
     strategy:
       max-parallel: 4
       matrix:
-        python-version: [3.6, 3.7, 3.8]
+        python-version: [3.8]
 
     steps:
       - uses: actions/checkout@v1

setup.py

@@ -55,8 +55,6 @@ setup(
     keywords='nyaggle kaggle',
     classifiers=[
         'License :: OSI Approved :: BSD License',
-        'Programming Language :: Python :: 3.6',
-        'Programming Language :: Python :: 3.7',
         'Programming Language :: Python :: 3.8'
     ]
 )