GitHub default branch should be main not master

[zengmao]

When generating a new package folder interactively, you need to manually change the default branch from master to main to comply with GitHub's current default (the latter). This needs to be updated.

[gdalle]

I think PkgTemplates is doing everything it can on this side:

https://github.com/JuliaCI/PkgTemplates.jl/blob/8b857be7f1ec51518d47d9464baa7cfa34d3f1f9/src/plugins/git.jl#L1-L15

The problem is likely further upstream, maybe libgit2 is still using master as default?

[nsajko]

I always use PkgTemplates via the interactive generate() process. FTR all of my new packages get main instead of master for a long time now. Not that I care.