fix: panic when the ctx is nil

[acehinnnqru]

What type of PR is this?

fix: set ctx as context.Background when it is nil

When the ctx is nil, the method Do will panic when it trying to call the ctx.Done().

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[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 72.19%. Comparing base (d0d9e25) to head (c4d8de3).

Files with missing lines	Patch %	Lines
pkg/protocol/http1/client.go	0.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1290      +/-   ##
===========================================
- Coverage    72.22%   72.19%   -0.03%     
===========================================
  Files          138      138              
  Lines        16137    16139       +2     
===========================================
- Hits         11655    11652       -3     
- Misses        3887     3891       +4     
- Partials       595      596       +1     

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