hack/regenerate_vendor_mocks.sh fails in ovnk repo

hack/regenerate_vendor_mocks.sh is the script we use to regenerate mock types and it is outdated: the `mockery` command fails whenever it's invoked by the script.

riccardo@work:~/go/src/github.com/ovn-org/ovn-kubernetes/go-controller/hack$ ./regenerate_vendor_mocks.sh 

04 Oct 22 15:52 CEST INF Starting mockery dry-run=false version=v2.9.4
mockery is already installed
../pkg/testing/mocks/k8s.io/utils/exec/ExitError.go
Error: unknown command "ExitError" for "mockery"
Run 'mockery --help' for usage.
../pkg/testing/mocks/k8s.io/utils/exec/Cmd.go
Error: unknown command "Cmd" for "mockery"
Run 'mockery --help' for usage.
../pkg/testing/mocks/k8s.io/utils/exec/Interface.go
Error: unknown command "Interface" for "mockery"
Run 'mockery --help' for usage.
../pkg/testing/mocks/k8s.io/client-go/listers/core/v1/PodTemplateNamespaceListerExpansion.go
Error: unknown command "PodTemplateNamespaceListerExpansion" for "mockery"
Run 'mockery --help' for usage.

... and so on