v1.3.0: Upload sbomnix sbom to github release artifacts

- Upload runtime and buildtime SBOMs from sbomnix itself to
  release artifacts on every push of a new release tag
- Up the sbomnix version to v1.3.0

Signed-off-by: Henri Rosten <[email protected]>

Release v1.2.0

Up the version to 1.2.0

Signed-off-by: Henri Rosten <[email protected]>

Release v1.1.0

Merge pull request #34 from henrirosten/fixes_from_manually_testing_o…

…n_nixos

misc: fixes from manual testing on nixos

Release v1.0.0

Merge pull request #25 from henrirosten/readme_fix_toc

doc: fix toc in main readme