v1.0.0-rc9

What's Changed

• test: drop references to docker:// images from test/ by @smoser in #547
• test: add busybox image, use it to replace centos image. by @smoser in #545
• test: Fix the docker-clone make target to exit failure. by @smoser in #551
• ci: add a job to sync 3rd party container images by @rchincha in #546
• ci: fix image dest during copy by @rchincha in #552
• test: add code coverage support by @rchincha in #550
• test: Fix test failure due to .coverage changing during tar creation. by @smoser in #557
• ci: Upload stacker binary by @smoser in #556
• ci: fix upload order by @rchincha in #559
• fix: alpine bom by @rchincha in #561
• feat: Support legacy 'import' directive and use 'imports' for future by @smoser in #543
• test: add a bom workflow with substitutions by @rchincha in #562
• revert: "test: add a bom workflow with substitutions (#562)" by @rchincha in #563
• Fix bom test failures by @smoser in #564

Full Changelog: v1.0.0-rc8...v1.0.0-rc9