Update dandi gui-staging url to sandbox (#613)

* rename gui-staging to sandbox

* update urls

Author: stephprince

.github/workflows/dev-gallery.yml

@@ -30,7 +30,7 @@ jobs:
           pip install git+https://github.com/neurodatawithoutborders/pynwb@dev
 
       - name: Download testing data and set config path
-        run: dandi download "https://gui-staging.dandiarchive.org/#/dandiset/204919"
+        run: dandi download "https://sandbox.dandiarchive.org/#/dandiset/204919"
 
       - name: Run pytest
         run: pytest -rsx

.github/workflows/testing.yml

@@ -33,7 +33,7 @@ jobs:
       - name: Install package
         run: pip install ".[dandi]"
       - name: Download testing data and set config path
-        run: dandi download "https://gui-staging.dandiarchive.org/#/dandiset/204919"
+        run: dandi download "https://sandbox.dandiarchive.org/#/dandiset/204919"
 
       - name: Run pytest with coverage
         run: pytest -rsx --cov=nwbinspector --cov-report xml:./coverage.xml