[Gemspec] - Allow lower faraday versions

[itstheraj]

Description

In reference to issue: #172 - this CR exists to allow for applications requiring different, lower Faraday versions to integrate with this Gem.

Changes Made

1. Updated the gemspec for Faraday and its dependencies to allow use of lower versions in case of a conflict.
2. Updated CICD.yml workflow to validate that lower Faraday versions work.
3. Specs failed on lower Faraday versions so I updated lib/ruby_llm/streaming.rb to allow for legacy Faraday versions to stream responses as well. Could use feedback definitely in case this breaks logic in a way you all are uncomfy with.

Testing

I ran manually rspec with Faraday Version 2.13.1 and 1.10.3, here are the results prior to CI/CD integration in this repo:

Faraday Version	Validate Gem Install	Test Results
1.10.3
2.13.1

[codecov]

Codecov Report

Attention: Patch coverage is 69.23077% with 8 lines in your changes missing coverage. Please review.

Project coverage is 91.06%. Comparing base (8b16d38) to head (df46d16).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/ruby_llm/streaming.rb	69.23%	8 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #173      +/-   ##
==========================================
- Coverage   91.29%   91.06%   -0.23%     
==========================================
  Files          91       91              
  Lines        3641     3661      +20     
  Branches      559      567       +8     
==========================================
+ Hits         3324     3334      +10     
- Misses        317      327      +10     

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