Re-run the percy job anytime the PR is changed

This is better than only running it when the label is applied, once
the label is on the PR it should run on each change.

.github/workflows/percy.yml

@@ -5,7 +5,7 @@ on:
     tags:
       - '*'
   pull_request_target:
-    types: [labeled]
+    types: [labeled,opened,reopened,synchronize]
   schedule:
     - cron: "15 23 * * 2,4" # T,Th in the afternoon (UTC)
   workflow_dispatch:
@@ -23,7 +23,7 @@ env:
 jobs:
   percy:
     name: Test and Capture Screenshots
-    if: ${{ github.event.action != 'labeled' || github.event.label.name == 'run percy tests' }}
+    if: contains(github.event.pull_request.labels.*.name, 'run percy tests')
     runs-on: ubuntu-latest
     timeout-minutes: 20
     steps: