Add recent browser PR merges to release notes

[ankur22]

What?

Add recent browser PR merges to release notes.

Why?

To keep users up to date with browser related changes.

Checklist

• I have performed a self-review of my code.
• I have added tests for my changes.
• I have run linter locally (make lint) and all checks pass.
• I have run tests locally (make tests) and all tests pass.
• I have commented on my code, particularly in hard-to-understand areas.

Related PR(s)/Issue(s)

grafana/xk6-browser#1259
grafana/xk6-browser#1260
grafana/xk6-browser#1261
grafana/xk6-browser#1262
grafana/xk6-browser#1264

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

❗ No coverage uploaded for pull request base (release-v0.51.0@8489f8d). Click here to learn what that means.

❗ Current head 885cee3 differs from pull request most recent head 1248e4d. Consider uploading reports for the commit 1248e4d to get more accurate results

Additional details and impacted files

@@                Coverage Diff                 @@
##             release-v0.51.0    #3709   +/-   ##
==================================================
  Coverage                   ?   73.57%           
==================================================
  Files                      ?      277           
  Lines                      ?    20247           
  Branches                   ?        0           
==================================================
  Hits                       ?    14896           
  Misses                     ?     4403           
  Partials                   ?      948           

Flag	Coverage Δ
ubuntu	73.49% <ø> (?)
windows	73.43% <ø> (?)

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