Docker: Local Builds for Go Components fail

When trying to build, following error occurs:

=> ERROR [9/9] RUN go build -o ./remote_integrity ./cmd/cam-collection-integrity/cam-collection-integrity.go                                                                                                0.9s
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 > [9/9] RUN go build -o ./remote_integrity ./cmd/cam-collection-integrity/cam-collection-integrity.go:                                                                                                           
#13 0.819 service/collection/integrity/server.go:38:2: no required module provides package gitlab.com/gaia-x/data-infrastructure-federation-services/cam/internal/testutil; to add it:
#13 0.819       go get gitlab.com/gaia-x/data-infrastructure-federation-services/cam/internal/testutil