tools: upgrade trivy to v0.30.3

Created by: bobheadxi

I'm currently unable to install 0.20.0 locally - it seems it has no distribution for M1 macs - but the latest version, 0.30.3, works fine for me.

Test plan

Main dry run to build and scan the images: https://buildkite.com/sourcegraph/sourcegraph/builds/163111