Disallow indefinite http client timeout

[avalonche]

📝 Summary

Ensure that timeout for relay requests to be greater than 0.

⛱ Motivation and Context

0 and negative timeout values result in no timeout, which a malicious relay can potentially block execution, especially in the handleGetHeader function.

📚 References

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✅ I have run these commands

• make lint
• make test
• make run-mergemock-integration
• go mod tidy

[codecov-commenter]

Codecov Report

Merging #210 (5a2ad4f) into main (df5e354) will decrease coverage by 0.22%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main     #210      +/-   ##
==========================================
- Coverage   72.16%   71.94%   -0.23%     
==========================================
  Files           6        6              
  Lines         636      638       +2     
==========================================
  Hits          459      459              
- Misses        151      153       +2     
  Partials       26       26              

Flag	Coverage Δ
unittests	71.94% <0.00%> (-0.23%)	⬇️

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

Impacted Files	Coverage Δ
cmd/mev-boost/main.go	4.54% <0.00%> (-0.11%)	⬇️

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