Release candidate 1 for version 1.0 of the SPDX Maven Plugin

NOTE: This release contains some significant changes to support SPDX spec version 3 - so it is designated as a release candidate.

What's Changed

• Add support for SPDX Spec Version 3 by @goneall in #171
• Adding an aggregateSpdx goal by @ctjosey in #174
• Add option to filter scopes when creating SBOM by @stgrace in #173
• Update SPDX Java libraries by @goneall in #175

New Contributors

• @ctjosey made their first contribution in #174
• @stgrace made their first contribution in #173

Full Changelog: v0.7.4...v1.0.0-RC1