fix gRPC timeout (#1498)

[spadger]

Fixes #1498 (grpc timeouts not being respected)

The timeout seems to work correctly for long and short variants of the bug with this code but I wasn't able to create meaningful tests. Whilst it was possible to get the calculated timeval from the transport instance using reflection, actually calling functions on \Grpc\Timeval (such as similar() just crashes the test runner

No additional unit tests fail compared to main (35 vs 35)
Happy to make any adjustments according to feedback

[welcome]

Thanks for opening your first pull request! If you haven't yet signed our Contributor License Agreement (CLA), then please do so that we can accept your contribution. A link should appear shortly in this PR if you have not already signed one.

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 1 line in your changes missing coverage. Please review.

Project coverage is 70.78%. Comparing base (96ce422) to head (922e120).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/Contrib/Grpc/GrpcTransport.php	50.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1499      +/-   ##
============================================
+ Coverage     70.76%   70.78%   +0.01%     
  Complexity     2762     2762              
============================================
  Files           408      408              
  Lines          8343     8344       +1     
============================================
+ Hits           5904     5906       +2     
+ Misses         2439     2438       -1     

Flag	Coverage Δ
8.1	70.53% <66.66%> (+0.05%)	⬆️
8.2	70.64% <66.66%> (-0.01%)	⬇️
8.3	70.72% <66.66%> (+0.07%)	⬆️
8.4	70.75% <66.66%> (+0.07%)	⬆️
8.5	70.66% <66.66%> (-0.01%)	⬇️

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

Files with missing lines	Coverage Δ
src/Contrib/Grpc/GrpcTransportFactory.php	71.79% <100.00%> (ø)
src/Contrib/Grpc/GrpcTransport.php	47.22% <50.00%> (+1.50%)	⬆️

... and 5 files with indirect coverage changes

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 96ce422...922e120. Read the comment docs.

[brettmc]

LGTM - with no collector available I was able to test that the timeout is accurate for <5s values. Beyond 5s, I got a host lookup error which occurred at 5s if the configured timeout doesn't kick in first.

Can you please fix the linting error (make style locally, if you're using our test image etc)