v0.15.0 - add sigstore signing of all images, auto-updating vulnerability summary, and many dependabot bumps

Changes

• add another matrix dimension to container hooks @some-natalie (#281)
• container scaling test uses multiple containers on same runner set @some-natalie (#280)
• bump runner and fix linter nags @some-natalie (#279)
• bump runner to 2.321.0 @some-natalie (#277)
• bump deps @some-natalie (#276)
• try this to push all tags @some-natalie (#272)
• dependency bumps @some-natalie (#269)
• bump deps @some-natalie (#268)
• the better way to dismiss alerts on other architectures @some-natalie (#267)
• only scan on one architecture to dedupe results @some-natalie (#266)
• bump docker and compose @some-natalie (#265)
• readme update script to include architectures @some-natalie (#264)
• bump runner @some-natalie (#262)
• bump runner to 2.319.0 @some-natalie (#261)
• bump dependencies @some-natalie (#259)
• bump docker @some-natalie (#257)

🧰 Maintenance

• Bump anchore/scan-action from 4 to 5 @dependabot (#270)
• Bump super-linter/super-linter from 6 to 7 @dependabot (#263)
• Bump anchore/scan-action from 3 to 4 @dependabot (#258)