Fix inconsisten vendoring issue due the self replace

[arbulu89]

Fix for in go1.18 during the make build action:

go: inconsistent vendoring in /home/xarbulu/Workspace/sap_squad/trento-stack/runner:
	github.com/trento-project/runner: is marked as replaced in vendor/modules.txt, but not replaced in go.mod

	To ignore the vendor directory, use -mod=readonly or -mod=mod.
	To sync the vendor directory, run:
		go mod vendor
make: *** [Makefile:45: trento-runner] Error 1

Some related external discussions:
containerd/containerd#6586
golang/go#34417

Apparently the self replace thing is not supported anymore in golang 1.18, since it doesn't make many sense.
@stefanotorresi Could you have a special look on this, since I don't really know why we started having this thing in the code

[dottorblaster]

If the CI is happy I'm happy as well

[stefanotorresi]

I think that line was originally in the monolithic repo. If removing it doesn't break anything, go with it.