Git is a unique beast. Takes a while to get used to it.
There’s a short answer, but I want to take a detour because Gramps developer workflow promotes Pull Requests as opposed to direct commits to the Gramps repositories (which it appears you’re attempting to do above), and you were stopped for an unrelated reason (your local repo is not in sync with the origin).
Here’s some reading material which you can review later: Working with development branches (from Gramps wiki)
And a fair warning: Please make copies of your modified files in case something goes wrong. I believe the commands I am giving you will work, but I’m not at your desk, so better take precaution.
I see that you seem to have write access to gramps-project/addons-source. You start by cloning the repo and before you start making changes, it’s encouraged that you create your own branch for your new work and give it a good name. I see that you are working in a branch named maintenance/gramps60, but that is a published branch used by everyone, and it’s best not to commit your new files into that until the files are reviewed in a PR, approved and committed. So first, create a local branch for this work, say bruno-ancestry-table-report which will track the maintenance/gramps60 branch from origin (more on this later) which is your target branch:
git checkout -b bruno-ancestry-table-report --track origin/maintenance/gramps60
This creates a work area in your local machine where you can make changes you want, test, and when ready, add, commit, and push your branch (not just modified files) up to the origin (i.e. from where you cloned the repo). Now it looks like you’ve already committed your files to your local maintenance/gramps60 so we need to update the new branch to be based on those changes:
git rebase maintenance/gramps60
(Note, the local branch might be gramps60 if that’s what you named it - check using git branch -v). Anyway, rebase is git magic
What it did was to take the changes you had in that branch and based your current branch bruno-ancestry-table-report on top of that. So if you type in git log you should see all your previous commits.
Good so far? If so, now’s the time to fetch the latest changes from origin (GitHub) which is where you were stuck, and then push your changes:
git pull --rebase
git push
The first command will pull newer files from your tracking branch and then rebase your branch on that. Then you push. Now if you go to the Gramps project on GitHub, you will see a message saying that a new branch has been pushed and you can create a Pull Request from it. Go ahead and do that, add notes to your Pull Request for the reviewers, and assign reviewers if you have permission and your code will be up for others to comment on.
Hope this helps! Feel free to ask if something isn’t clear.