Rename the master branch to main

[oleg-nenashev]

Summary

We do not have a position on naming in the community yet, but it is better to follow the standards to improve discoverability of the repositories and attract contributors

References

No response

[mikeywaites]

When this is actioned we need to also remember to update the branch pattern matching in .github/workflows/tests.yaml

[oleg-nenashev]

Well, it would be better to rename rather sooner than later. Otherwise we'll be accumulating technical debt