Rename `master` branch to `main`

[PProfizi]

Objectives

• do not impact other repositories with dependency on pydpf repositories -> implement a redirect? implement a deprecation message
• how do we share an automatic way to fix the issue

Technical solutions to switch from master to main flawlessly:

• redirects with symlinks -> works for some cases of direct branch reference, but not for actions
• even a simple rename of the branch is handled by github in some cases
• git-hooks -> impossible to share or enforce locally, but we can version some

Planning:

• make announcement with deprecation period
• the fix should be available and fixable right away
• maintain main and master during deprecation period

Use-cases:

• ansys developers: reach them with internal communication
  • announcements in Teams, in PyAnsys meetings, PyAnsys AFT meetings
• channel partners and outside collaborators:
  • org-level announcement, repo announcement discussion, README?,

@moe-ad @jorgepiloto @ansjhajjar

[PProfizi]

Planning:

• make a new branch main
• make the action sync master with main and make main the default branch
• communicate the deprecation of master in a month, with the quick way to switch
• make PRs on TFS side and everywhere else
• after the deprecation period, remove master