Add latest milestone to generate_milestone_reports.py

Change-Id: I49587bae7c1a7a3284ffe8563b694d84539e09a9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2039981
Auto-Submit: Mohamed Heikal <mheikal@chromium.org>
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#738798}

tools/binary_size/generate_milestone_reports.py

@@ -73,6 +73,7 @@ _DESIRED_VERSIONS = [
     '78.0.3904.62',
     '79.0.3945.79',  # Beta
     '80.0.3987.20',  # Canary
+    '81.0.4044.10',
 ]