Update coverity version message

[chinglee-iot]

Update coverity version message

Description

In this PR:

• Update coverity version to 2023.6.1
• Replace CMake variable "UNIT_TESTS" with "UNITTEST", "COVERITY" with "COV_ANALYSIS" to align with FreeRTOS libraries

Test Steps

Checklist:

• I have tested my changes. No regression in existing tests.
• I have modified and/or added unit-tests to cover the code changes in this Pull Request.

Related Issue

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.02%. Comparing base (e0cd4db) to head (412636d).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #191   +/-   ##
=======================================
  Coverage   94.02%   94.02%           
=======================================
  Files           3        3           
  Lines        1690     1690           
  Branches      442      442           
=======================================
  Hits         1589     1589           
  Misses         17       17           
  Partials       84       84           

Flag	Coverage Δ
unit_tests	94.02% <ø> (ø)

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