Name is duplicated into Package URL Namespace when Go module path has one element

[ribbybibby]

What happened:
I noticed that the module name is duplicated into the namespace of the purl for go.opencensus.io:

pkg:golang/go.opencensus.io/go.opencensus.io@v0.23.0

What you expected to happen:
I would expect a purl like this:

pkg:golang/go.opencensus.io@v0.23.0

How to reproduce it (as minimally and precisely as possible):

$ syft prom/prometheus@sha256:df0cd5887887ec393c1934c36c1977b69ef3693611932c3ddeae8b7a412059b9 -o cyclonedx-json 2> /dev/null \
  | jq -r '.components[] | select(.name == "go.opencensus.io") | .purl'
pkg:golang/go.opencensus.io/go.opencensus.io@v0.23.0

Environment:

$ syft version
Application:        syft
Version:            0.50.0
JsonSchemaVersion:  3.3.0
BuildDate:          2022-07-06T13:43:38Z
GitCommit:          69134ed3b54bc8b1d86d868611f7d069ce3290a8
GitDescription:     v0.50.0
Platform:           linux/amd64
GoVersion:          go1.18.3
Compiler:           gc