Update help_app to xWPW8iOCFFb9BXbsulgdmAJ8knCb8NlzyKzfh1Tst2AC CIPD package.

CIPD package: https://chrome-infra-packages.appspot.com/p/chromeos_internal/apps/help_app/app/+/xWPW8iOCFFb9BXbsulgdmAJ8knCb8NlzyKzfh1Tst2AC

Release notes: http://go/help_app-x20/relnotes/Nightly/help_app_nightly_202006240800_RC00.html

Cq-Include-Trybots: chrome/try:linux-chromeos-chrome
Change-Id: Ieb0893c0edbe619f1c13f7604841f815f742d14e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2266233Reviewed-by: Rachel Carpenter <carpenterr@chromium.org>
Commit-Queue: Zufeng Wang <zufeng@google.com>
Cr-Commit-Position: refs/heads/master@{#782821}

DEPS

@@ -1538,7 +1538,7 @@ deps = {
     'packages': [
       {
         'package': 'chromeos_internal/apps/help_app/app',
-        'version': 'EzR30mgq8gBio73c57P_BOSZHQ1vp_pejDwHKnzEKO4C',
+        'version': 'xWPW8iOCFFb9BXbsulgdmAJ8knCb8NlzyKzfh1Tst2AC',
       },
     ],
     'condition': 'checkout_chromeos and checkout_src_internal',