try to restrict percy to a single width, and longer timeout

Author: alexcjohnson

.circleci/config.yml

@@ -263,7 +263,7 @@ jobs:
           name: Run percy snapshots
           command: |
             npm i @percy/cli
-            npx percy snapshot test/percy/
+            npx percy snapshot -c test/percy/snapshots.yml test/percy/
             rm test/percy/*.html
 
   # Chart studio

.gitignore

@@ -52,3 +52,5 @@ doc/check-or-enforce-order.py
 packages/javascript/jupyterlab-plotly/lib/
 packages/python/plotly/jupyterlab_plotly/labextension/
 packages/python/plotly/jupyterlab_plotly/nbextension/index.js*
+
+test/percy/*.html

test/percy/snapshots.yml

@@ -0,0 +1,7 @@
+version: 2
+static:
+  options:
+    waitForTimeout: 3000
+snapshot:
+  widths:
+    - 1280