Padding repetition number? #87

Hello,
first of all, thank you for this plugin and all of your other work.

Would you be OK to update the test name by padding the iteration number?
I foresee a benefit in consuming the reports.
For instance when used in conjunction with pytest-html, sorting the tests by name would happen properly in the HTML report.

Right now, if I repeat a test 10 times, sorting the tests by name would look like:

test_something.py::test_do_nothing[1-10]
test_something.py::test_do_nothing[10-10] # this is out of order
test_something.py::test_do_nothing[2-10]
test_something.py::test_do_nothing[3-10]
# [...]

By padding wih either 0 or ' ', simple sorting would work

PASSED test_something.py::test_do_nothing[ 1-10]
PASSED test_something.py::test_do_nothing[ 2-10]
PASSED test_something.py::test_do_nothing[ 3-10]
# [...]
PASSED test_something.py::test_do_nothing[10-10]

I also prefer the way it gets printed on console during execution, but it is just a matter of personal taste.

I am happy to submit a working patch, if you like this proposal.
In case, let me know which padding character you prefer between 0 or ' '.

Kind regards,
Filippo