replace master with main

[andrewpearce-digital]

Purpose

rename default branch to avoid use of charged or offensive terms

Fixes UML-1832

Approach

• replace master with main in all references in circleci pipeline and github actions workflows

Learning

https://github.com/github/renaming

Checklist

• I have performed a self-review of my own code
• The product team have tested these changes

[codecov]

Codecov Report

Merging #1159 (6455007) into master (1824537) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master    #1159   +/-   ##
=========================================
  Coverage     91.62%   91.62%           
  Complexity     1384     1384           
=========================================
  Files           226      226           
  Lines          4251     4251           
  Branches         22       22           
=========================================
  Hits           3895     3895           
  Misses          356      356           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 1824537...6455007. Read the comment docs.