Move to python3 venv and update vscode settings (stripe#1123)

.vscode/extensions.json

@@ -1,6 +1,7 @@
 {
   "recommendations": [
     "ms-python.python",
-    "EditorConfig.editorconfig"
+    "EditorConfig.editorconfig",
+    "ms-python.flake8",
   ]
 }

.vscode/settings.json

@@ -10,15 +10,11 @@
 
   // Formatting
   "editor.formatOnSave": true,
-  "python.formatting.provider": "black",
-
-  // Linting
-  "python.linting.enabled": true,
-  "python.linting.pylintEnabled": false,
-  "python.linting.flake8Enabled": true,
 
   // Tests
   "python.testing.unittestEnabled": false,
   "python.testing.pytestEnabled": true,
-  "python.testing.nosetestsEnabled": false
+
+  "python.terminal.activateEnvironment": true,
+  "python.defaultInterpreterPath": "~/venv/bin/python3"
 }

Makefile

@@ -1,12 +1,11 @@
 VENV_NAME?=venv
 PIP?=pip
-PYTHON?=python
+PYTHON?=python3
 
 venv: $(VENV_NAME)/bin/activate
 
-$(VENV_NAME)/bin/activate: setup.py
-	$(PIP) install --upgrade pip virtualenv
-	@test -d $(VENV_NAME) || $(PYTHON) -m virtualenv --clear $(VENV_NAME)
+$(VENV_NAME)/bin/activate: setup.py requirements.txt
+	@test -d $(VENV_NAME) || $(PYTHON) -m venv --clear $(VENV_NAME)
 	${VENV_NAME}/bin/python -m pip install -r requirements.txt
 	@touch $(VENV_NAME)/bin/activate