Run Percy Nightly and on PR (#4540)

Previously this was only running on wednesdays

.github/workflows/e2e-visual.yml

@@ -1,16 +1,15 @@
 name: "e2e-visual"
 on:
   workflow_dispatch:
-    inputs: 
-      version:
-        description: '(Not configured) Which branch do you want to test?' # Limited to branch for now
-        required: false
-        default: 'master'
+  pull_request:
+    types: 
+      - labeled
   schedule:
-    - cron: '28 21 * * 3'
+    - cron: '28 21 * * 1-5'
 
 jobs:
   e2e-visual:
+    if: ${{ github.event.label.name == 'pr:visual' }} || ${{ github.event.workflow_dispatch }} || ${{ github.event.schedule }}
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2