raise error on duplicate ports passed to patch

[PietroPasotti]

Issue

the service patch silently fails if you pass duplicate ports to it, say

                ports=[
                    ServicePort(name="svc1", port=1234, protocol="TCP"),
                    ServicePort(name="svc2", port=1234, protocol="TCP"),
                ],

Solution

catch that and raise an exception as that's user error

Context

this would have saved me a couple of hours of debugging this week