fix(requests): preventConcurrentRequest along with staleTime

[citruspress]

This fixes #485

PR Checklist

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• The commit message follows our guidelines: https://github.com/ngneat/elf/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
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PR Type

What kind of change does this PR introduce?

trackRequestResult no longer considers staleTime when skipping a request with status: fetching.

[x] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

It's currently possible to have concurrent requests even if preventConcurrentRequest is true because all requests that are 'fetching' are also stale.

Issue Number: #485

What is the new behavior?

The stale time is not considered at all when deciding wether to skip a request or not for fetching requests.

An alternative solution would be to set the stale time for request that are fetching, but this seems like a cleaner solution.

Does this PR introduce a breaking change?

[ ] Yes
[x] No

I cannot see a reason this would be breaking.

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