generate_milestone_reports.py: Add 87.0.4280.13

Change-Id: I6ee9728be16e04f62982258323f00cf91bb35589
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2460227
Auto-Submit: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Samuel Huang <huangs@chromium.org>
Commit-Queue: Samuel Huang <huangs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#815019}

tools/binary_size/generate_milestone_reports.py

@@ -75,6 +75,7 @@ _DESIRED_VERSIONS = [
     '84.0.4147.89',
     '85.0.4183.81',
     '86.0.4240.11',  # Canary
+    '87.0.4280.13',  # Canary
 ]