chore: specify dev dependencies in setup.cfg

README.md

@@ -103,7 +103,6 @@ run:
 ```
 python3 -m venv venv
 . venv/bin/activate
-pip install pytest tox black pytest-xdist pytest-timeout
-pip install -e .
+pip install -e .[dev]
 tox
 ```

setup.cfg

@@ -26,6 +26,14 @@ install_requires =
     qrcode
     deltachat>=1.136.2
 
+[options.extras_require]
+dev =
+    pytest
+    tox
+    black
+    pytest-xdist
+    pytest-timeout
+
 [options.packages.find]
 where = src