docs: update README to include conda

[kmnhan]

Description

Adding badge and instructions for conda-forge to README since #526 has been addressed.

Checklist

• Add test cases to all the changes you introduce
• Run ./scripts/format and ./scripts/test locally to ensure this change passes linter check and test
• Test the changes on the local machine manually
• Update the documentation for the changes

Expected behavior

Steps to Test This Pull Request

Additional context

Closes: #526

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.66%. Comparing base (120d514) to head (b3ac145).
Report is 453 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1256      +/-   ##
==========================================
+ Coverage   97.33%   97.66%   +0.33%     
==========================================
  Files          42       55      +13     
  Lines        2104     2575     +471     
==========================================
+ Hits         2048     2515     +467     
- Misses         56       60       +4     

Flag	Coverage Δ
unittests	97.66% <ø> (+0.33%)	⬆️

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