Note all in contributing docs

CONTRIBUTING.md

@@ -35,7 +35,7 @@ Ready to contribute? Here's how to set up pyribs for local development.
    cd pyribs
    conda create --prefix ./env python=3.8 # 3.8 is the minimum version pyribs supports.
    conda activate ./env
-   pip install -e .[dev]
+   pip install -e .[all,dev]
    ```
 
 1. We roughly follow the