ci: drop sha-* image tags

:main already tracks the head of main mutably, and version tags
take over once releases are cut. The sha-* tags just clutter the
Packages page without an extra debug path the digest doesn't
already give.

Author: e-scheer

.github/workflows/ci.yml

@@ -111,7 +111,6 @@ jobs:
             type=ref,event=branch
             type=semver,pattern={{version}}
             type=semver,pattern={{major}}.{{minor}}
-            type=sha,prefix=sha-,format=short
             type=raw,value=latest,enable=${{ startsWith(github.ref, 'refs/tags/v') }}
 
       - name: Build & push multi-arch image