python3-robotframework: upgrade 6.0.2 -> 6.1

Changelog:
https://github.com/robotframework/robotframework/blob/master/doc/releasenotes/rf-6.1.rst



Signed-off-by: Wang Mingyu <wangmy@fujitsu.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>