drop python 3.6 support

.github/workflows/pythonpackage.yml

@@ -17,7 +17,7 @@ jobs:
     strategy:
       max-parallel: 4
       matrix:
-        python-version: ['3.6', '3.7', '3.8', '3.9', '3.10']
+        python-version: ['3.7', '3.8', '3.9', '3.10']
 
     steps:
     - uses: actions/checkout@v2

.travis.yml

@@ -3,7 +3,6 @@ os: linux
 dist: focal
 
 python:
-  - "3.6"
   - "3.7"
   - "3.8"
   - "3.9"

pyproject.toml

@@ -11,7 +11,6 @@ keywords = ["icalendar", "sync", "google", "calendar"]
 classifiers = [
     'License :: OSI Approved :: MIT License',
     'Operating System :: OS Independent',
-    'Programming Language :: Python :: 3.6',
     'Programming Language :: Python :: 3.7',
     'Programming Language :: Python :: 3.8',
     'Programming Language :: Python :: 3.9',
@@ -19,7 +18,7 @@ classifiers = [
 ]
 
 [tool.poetry.dependencies]
-python = "^3.6"
+python = "^3.7"
 google-auth = "2.6.0"
 google-api-python-client = "2.36.0"
 icalendar = "4.0.9"