Do not push with --allow-empty if there are no changes

[vsoch]

Currently, the workflows will still open a pull request or commit if there are no changes to the graphic. Although this is unlikely for an active repository, we should remove the --allow-empty and catch the error and still return success if it's not opened. There might be a better command to do the check, but first I'm just going to try adding || echo "No changes"

[vsoch]

Testing locally - when there are no changes the exit status is 1

$ git commit -a -s -m 'there are no changes'
echo $?
1

So instead we can do

$ git commit -a -s -m 'there are no changes' || echo "No changes"
echo $?
0