Update CI, Add Ruby 3.x

[otherguy]

Changes

• Update CircleCI pipeline to use matrix job
• Add Ruby 3.x to tested versions
• Add Depfu configuration
• Add Sonarcloud configuration
• Update dependencies to resolve vulnerability alerts

Deprecations

• Ruby 2.5 and 2.6, which are EOL since 2021 and 2022, respectively
• Faraday 0.15, which does not work with Ruby 3.x

[codecov]

Codecov Report

Attention: Patch coverage is 40.00000% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 99.18%. Comparing base (eb12e12) to head (26bb274).
Report is 4 commits behind head on main.

Files	Patch %	Lines
lib/remove_bg/upload.rb	40.00%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##              main      #21      +/-   ##
===========================================
- Coverage   100.00%   99.18%   -0.82%     
===========================================
  Files           16       16              
  Lines          362      366       +4     
===========================================
+ Hits           362      363       +1     
- Misses           0        3       +3     

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[sonarcloud]

Quality Gate passed

Issues
66 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud