Updated contributing.md

added support for zsh

Author: wgottwald

docs/contributing.md

@@ -16,13 +16,8 @@ pre-commit install
 
 The `conda env create` command installs all Python packages that are useful when working on the source code of `mpl_interactions` and its documentation. You can also install these packages separately:
 
-```bash
-pip install -e .[dev]
-```
-for MacOs systems that use zsh instead of bash type:
 ```bash
 pip install -e ".[dev]"
-
 ```
 
 The {command}`-e .` flag installs the `mpl_interactions` folder in ["editable" mode](https://pip.pypa.io/en/stable/cli/pip_install/#editable-installs) and {command}`[dev]` installs the [optional dependencies](https://setuptools.readthedocs.io/en/latest/userguide/dependency_management.html#optional-dependencies) you need for developing `mpl_interacions`.