Drop python3.6 support

Follows suite of flask and cryptography packages.

Author: vimalloc

.github/workflows/type_check.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python: [3.6, 3.7, 3.8, 3.9, '3.10']
+        python: [3.7, 3.8, 3.9, '3.10']
 
     steps:
       - uses: actions/checkout@v2

.github/workflows/unit_tests.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python: [3.6, 3.7, 3.8, 3.9, '3.10', pypy3]
+        python: [3.7, 3.8, 3.9, '3.10', pypy3]
 
     steps:
       - uses: actions/checkout@v2

setup.py

@@ -35,7 +35,7 @@
         "typing_extensions>=3.7.4; python_version<'3.8'",  # typing.Literal
     ],
     extras_require={"asymmetric_crypto": ["cryptography>=3.3.1"]},
-    python_requires=">=3.6,<4",
+    python_requires=">=3.7,<4",
     classifiers=[
         "Development Status :: 5 - Production/Stable",
         "Environment :: Web Environment",

tox.ini

@@ -4,7 +4,7 @@
 # and then run "tox" from this directory.
 
 [tox]
-envlist = py36,py37,py38,py39,py310,pypy3,mypy,coverage,style,docs
+envlist = py37,py38,py39,py310,pypy3,mypy,coverage,style,docs
 
 [testenv]
 commands =