Backport- Fixed race condition in AWSV4SignerAuth & AWSV4SignerAsyncAuth when using refreshable credentials

[saimedhi]

Description

Backport #470 to 2.3. Fixed race condition in AWSV4SignerAuth & AWSV4SignerAsyncAuth when using refreshable credentials

Issues Resolved

Related to #472

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[codecov[bot]]

Codecov Report

Merging #473 (6da9190) into 2.3 (f108677) will increase coverage by 0.00%. The diff coverage is 100.00%.

@@           Coverage Diff           @@
##              2.3     #473   +/-   ##
=======================================
  Coverage   70.91%   70.92%           
=======================================
  Files          81       81           
  Lines        7730     7732    +2     
=======================================
+ Hits         5482     5484    +2     
  Misses       2248     2248           

Files Changed	Coverage Δ
opensearchpy/helpers/asyncsigner.py	95.83% <100.00%> (+0.18%)	:arrow_up:
opensearchpy/helpers/signer.py	94.73% <100.00%> (+0.14%)	:arrow_up:

[saimedhi]

Sorry, I missed DCO. I hope it won't create any problem. Can I release this patch version?

[dblock]

I force-pushed a DCO fix to 2.3.

Let's go a little slower and not merge things on red.