removed unused environments and workflows (#1651)

* removed unused environments and workflows

* added v3 contributor guide

* add shell

Author: rabernat

.github/workflows/minimal.yml

@@ -0,0 +1,49 @@
+# V3 Contributor Guide
+
+A bare-bones guide to contributing to V3.
+
+Developed for the Feb. 2024 Zarr Sprint.
+
+## Clone V3 branch
+
+[Fork](https://github.com/zarr-developers/zarr-python/fork) zarr-python and clone it locally.
+
+```
+git clone {your remote}
+git remote add upstream https://github.com/zarr-developers/zarr-python
+git fetch upstream
+git checkout --track upstream/v3
+```
+
+## Set up your environment
+
+Zarr uses [hatch](https://hatch.pypa.io/) for its build system.
+
+```
+mamba install hatch
+```
+
+or
+
+```
+pip install hatch
+```
+
+Then
+
+```
+hatch env create test
+```
+
+## Run the Tests
+
+```
+hatch run test:run 
+```
+
+or
+
+```
+hatch -e test shell
+pytest -v
+```