Add k6 browser hot fix for networking deadlock

[inancgumus]

What?

Fixes a deadlock bug in k6-browser's networking component.

Why?

To let users continue to run browser tests without deadlocks.

Checklist

• I have performed a self-review of my code.
• I have added tests for my changes (see).
• I have run linter locally (make ci-like-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#1072

[codecov-commenter]

Codecov Report

Attention: 17 lines in your changes are missing coverage. Please review.

Comparison is base (5ceb210) 72.81% compared to head (3890d41) 73.32%.
Report is 29 commits behind head on master.

❗ Current head 3890d41 differs from pull request most recent head d267c9b. Consider uploading reports for the commit d267c9b to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3425      +/-   ##
==========================================
+ Coverage   72.81%   73.32%   +0.51%     
==========================================
  Files         259      258       -1     
  Lines       20016    19645     -371     
==========================================
- Hits        14574    14405     -169     
+ Misses       4507     4355     -152     
+ Partials      935      885      -50     

Flag	Coverage Δ
ubuntu	73.25% <59.52%> (?)
windows	73.18% <59.52%> (+0.37%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
cmd/root.go	94.26% <100.00%> (ø)
js/bundle.go	85.90% <100.00%> (ø)
js/console.go	94.28% <100.00%> (+0.16%)	⬆️
js/summary.go	89.87% <100.00%> (ø)
output/csv/config.go	74.50% <ø> (-2.69%)	⬇️
js/modules/k6/grpc/client.go	82.74% <0.00%> (-0.64%)	⬇️
js/runner.go	86.42% <71.42%> (+1.58%)	⬆️
cloudapi/config.go	83.33% <35.71%> (-7.58%)	⬇️

... and 15 files with indirect coverage changes

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