Move requirements-dev.txt into setup.cfg

Author: wch

README.md

@@ -248,6 +248,6 @@ it](https://github.com/rstudio/py-shinywidgets/issues/new)!
 If you want to do development on `{shinywidgets}`, run:
 
 ```sh
-pip install -e .
+pip install -e ".[dev,test]"
 cd js && yarn watch
 ```

requirements-dev.txt

@@ -42,6 +42,17 @@ tests_require =
     pytest>=3
 zip_safe = False
 
+[options.extras_require]
+test =
+    pytest>=6.2.4
+dev =
+    black>=23.1.0
+    flake8==5.0.4;python_version<="3.7"
+    flake8>=6.0.0;python_version>"3.7"
+    isort>=5.11.2
+    pyright>=1.1.284
+    wheel
+
 [options.packages.find]
 include = shinywidgets, shinywidgets.*