Improve the git workflow for the template

[xmnlab]

Currently, if there is already any commit on the origin/upstream main branch .. the branch created by the cookiecutter will have conflicts when we want to open a PR.

Additionally maybe it is too verbose to add the info for upstream and origin https urls
we probably should use a different approach

[xmnlab]

we need to discuss a better approach for the initial branch.

[xmnlab]

current, scicookie creates a new branch with no history ... and when we want to create a PR it raises issue because the history of that new branch is totally different than the main branch ..

some ideas to fix that:

• check if the origin and upstream exists
• if it exists, before create any commit, we should:
  • run git stash for the changes in the new branch,
  • rebase it on top of upstream/main
  • run git stash pop
  • and create a new commit
• if upstream or origin doesn't exist, maybe we could keep the same workflow

[xmnlab]

done