Add Custom pytest Marker to Ease Development (#2628)

Co-authored-by: Bibo-Joshi <22366557+Bibo-Joshi@users.noreply.github.com>

.github/CONTRIBUTING.rst

@@ -85,6 +85,8 @@ Here's how to make a one-off code change.
 
    - Please ensure that the code you write is well-tested.
 
+        - In addition to that, we provide the `dev` marker for pytest. If you write one or multiple tests and want to run only those, you can decorate them via `@pytest.mark.dev` and then run it with minimal overhead with `pytest ./path/to/test_file.py -m dev`.
+
    - Don’t break backward compatibility.
 
    - Add yourself to the AUTHORS.rst_ file in an alphabetical fashion.

setup.cfg

@@ -30,6 +30,7 @@ filterwarnings =
 ;    Unfortunately due to https://github.com/pytest-dev/pytest/issues/8343 we can't have this here
 ;    and instead do a trick directly in tests/conftest.py
 ;    ignore::telegram.utils.deprecate.TelegramDeprecationWarning
+markers = dev: If you want to test a specific test, use this
 
 [coverage:run]
 branch = True