test: Adjust data count range in SpotlightTests

[philipphofmann]

Updated the expected data count range in the
SentrySpotlightTransportTests to allow for a wider variance in GZip compression results, changing the lower and upper bounds from ±20 to ±40 to avoid flakiness.

Test failed here https://github.com/getsentry/sentry-cocoa/actions/runs/18778698663/job/53579222897.

#skip-changelog

Closes #6550

[codecov]

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Additional details and impacted files

@@           Coverage Diff            @@
##             main     #6549   +/-   ##
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  Coverage        ?   86.311%           
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  Files           ?       451           
  Lines           ?     37191           
  Branches        ?     17205           
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  Hits            ?     32100           
  Misses          ?      4808           
  Partials        ?       283           

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[philprime]

LGTM, but to be honest this is a wide range and it seems that this test highly unstable. We might want to explore if GZip can be configured to be deterministic

[philipphofmann]

LGTM, but to be honest this is a wide range and it seems that this test highly unstable. We might want to explore if GZip can be configured to be deterministic

True, but honestly, I don't want to invest that time right now for Spotlight. I don't think many people are using it. At least I can't remember a user opening an issue or asking questions about it.

[philprime]

I was even thinking about suggesting we remove the tests of Spotlight instead of fixing them.

[philipphofmann]

I was even thinking about suggesting we remove the tests of Spotlight instead of fixing them.

Yes, me too. We can ditch this single test case if it still breaks in the future.