Update dependabot to install dependencies

[ghost]

Small PR to address these failures when dependabot attempts to run:

...
mocks/controller-runtime/client/generate.go:3: running "mockgen": exec: "mockgen": executable file not found in $PATH
pkg/aws/cloud.go:24: running "mockgen": exec: "mockgen": executable file not found in $PATH
pkg/aws/services/tagging.go:15: running "mockgen": exec: "mockgen": executable file not found in $PATH
pkg/deploy/externaldns/dnsendpoint_manager.go:20: running "mockgen": exec: "mockgen": executable file not found in $PATH
pkg/deploy/lattice/access_log_subscription_manager.go:16: running "mockgen": exec: "mockgen": executable file not found in $PATH
pkg/gateway/model_build_lattice_service.go:21: running "mockgen": exec: "mockgen": executable file not found in $PATH
pkg/k8s/finalizer.go:12: running "mockgen": exec: "mockgen": executable file not found in $PATH
pkg/model/core/stack.go:15: running "mockgen": exec: "mockgen": executable file not found in $PATH
pkg/webhook/core/mutator.go:10: running "mockgen": exec: "mockgen": executable file not found in $PATH
make: *** [Makefile:61: vet] Error 1
Error: Process completed with exit code 2.
...