Add PkgToSoftwareBOM.jl to SPDX's list of OSS tools

[hannahilea]

...which is here: https://spdx.dev/tools-community/

[SamuraiAku]

Submitted an announcement to the spdx-outreach list.

[nsajko]

It seems that, to add PkgToSoftwareBOM.jl to https://spdx.dev/use/tools/open-source-tools/, it's necessary to create an issue here: https://github.com/spdx/outreach

There's also this list: https://cyclonedx.org/tool-center/. It seems PRs are accepted here: https://github.com/CycloneDX/cyclonedx.org

[SamuraiAku]

Finally added to the list

https://spdx.dev/use/spdx-tools