Bump github.com/google/go-github from v52 to v64

[andygrunwald]

Context

This Pull Request updates github.com/google/go-github from v52 to v64.

This change requires an upgrade of the Go version:

go: upgraded go 1.19 => 1.21
go: added toolchain go1.23.0

This change has been introduced in go-github in v60:

• google/go-github@a516e21

go mod tidy

A go mod tidy has been executed to remove unrequited dependencies. This has been committed in 7372cac in case this is not accepted.

Why is this change helpful for library users?

The function UserFromContext returns a *github.User object:

gologin/github/context.go

Line 23 in ebfe7fb

func UserFromContext(ctx context.Context) (*github.User, error) {

Library users are bound to github.com/google/go-github/v56 and require manual transforming the v56 user object into a v64 object, in case the caller is using a higher / different version.