Update expiry date for block-external-form-redirects-no-gesture

Bug: 927509
Change-Id: Ifb35e635d8124850ed6819d3e8be76efbbb3ce95
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2416522Reviewed-by: Ted Choc <tedchoc@chromium.org>
Commit-Queue: Jochen Eisinger <jochen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#808038}

chrome/browser/flag-metadata.json

@@ -419,7 +419,7 @@
   {
     "name": "block-external-form-redirects-no-gesture",
     "owners": [ "jochen", "tedchoc" ],
-    "expiry_milestone": 86
+    "expiry_milestone": 89
   },
   {
     "name": "bluetooth-aggressive-appearance-filter",