Drop support for python3.6 (#444)

.github/workflows/ci.yml

@@ -16,10 +16,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [Ubuntu, MacOS, Windows]
-        python-version: ['3.6', '3.7', '3.8', '3.9', '3.10']
-        exclude:
-          - os: Windows
-            python-version: 3.6
+        python-version: ['3.7', '3.8', '3.9', '3.10']
     steps:
       - uses: actions/checkout@v2
 

README.md

@@ -7,7 +7,7 @@ This project aims to provide an improved experience when using Protobuf / gRPC i
 
 - Protobuf 3 & gRPC code generation
   - Both binary & JSON serialization is built-in
-- Python 3.6+ making use of:
+- Python 3.7+ making use of:
   - Enums
   - Dataclasses
   - `async`/`await`
@@ -371,7 +371,7 @@ datetime.datetime(2019, 1, 1, 11, 59, 58, 800000, tzinfo=datetime.timezone.utc)
 
 ### Requirements
 
-- Python (3.6 or higher)
+- Python (3.7 or higher)
 
 - [poetry](https://python-poetry.org/docs/#installation)
   *Needed to install dependencies in a virtual environment*

benchmarks/__init__.py

@@ -1 +0,0 @@
-

pyproject.toml

@@ -12,9 +12,8 @@ packages = [
 ]
 
 [tool.poetry.dependencies]
-python = ">=3.6.2,<4.0"
+python = "^3.7"
 black = { version = ">=19.3b0", optional = true }
-dataclasses = { version = "^0.7", python = ">=3.6, <3.7" }
 grpclib = "^0.4.1"
 jinja2 = { version = ">=3.0.3", optional = true }
 python-dateutil = "^2.8"
@@ -112,7 +111,7 @@ force_grid_wrap = 2
 src_paths = ["src", "tests"]
 
 [tool.black]
-target-version = ['py36']
+target-version = ['py37']
 
 [tool.doc8]
 paths = ["docs"]
@@ -130,7 +129,7 @@ omit = ["betterproto/tests/*"]
 legacy_tox_ini = """
 [tox]
 isolated_build = true
-envlist = py36, py37, py38, py310
+envlist = py37, py38, py310
 
 [testenv]
 whitelist_externals = poetry

src/betterproto/__init__.py

@@ -887,10 +887,10 @@ class Message(ABC):
         t = cls._type_hint(field.name)
 
         if hasattr(t, "__origin__"):
-            if t.__origin__ in (dict, Dict):
+            if t.__origin__ is dict:
                 # This is some kind of map (dict in Python).
                 return dict
-            elif t.__origin__ in (list, List):
+            elif t.__origin__ is list:
                 # This is some kind of list (repeated) field.
                 return list
             elif t.__origin__ is Union and t.__args__[1] is type(None):