feat: add CLA workflow caller

[kalphonse-rgb]

Purpose

To enforce the Contributor License Agreement (CLA) on the Thermodynamics.jl repository

To-do

• Add the CLA workflow caller (.github/workflows/cla.yml)

Content

• Added .github/workflows/cla.yml using the organization template.

---

• I have read and checked the items on the review checklist.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.46%. Comparing base (609ecb4) to head (01e600a).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #295   +/-   ##
=======================================
  Coverage   90.46%   90.46%           
=======================================
  Files          21       21           
  Lines        1080     1080           
=======================================
  Hits          977      977           
  Misses        103      103           

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