DEV: install pytest-sugar for devs, which adds progress bar for tests…

… and makes output much nicer imo.

setup_developers.sh

@@ -6,12 +6,14 @@
 # (as opposed to setup.sh which needs to be run each new terminal session)
 
 # dependencies used in tests + formatting/linting script
-# (these might already be installed into the S3DF env, if so the following
-# cmds should simply do nothing)
+# (these might already be installed into the S3DF env, if so the following cmds should simply do nothing)
 pip install pytest
 pip install pillow
 pip install ruff
 
+# nice output formatting for pytest
+pip install pytest-sugar
+
 # setup test_data submodule
 git submodule init
 git submodule update