implement logic for getting image architecture from scratch, instead of relying on google/go-containerregistry/crane.

[tigerinus]

Signed-off-by: Tiger Wang tigerwang@outlook.com

[codecov]

Codecov Report

Merging #42 (b5122be) into main (d350877) will increase coverage by 3.32%.
The diff coverage is 57.60%.

@@            Coverage Diff             @@
##             main      #42      +/-   ##
==========================================
+ Coverage   45.06%   48.39%   +3.32%     
==========================================
  Files          18       18              
  Lines        1014     1058      +44     
==========================================
+ Hits          457      512      +55     
+ Misses        476      452      -24     
- Partials       81       94      +13     

Impacted Files	Coverage Δ
pkg/docker/image.go	11.53% <0.00%> (-0.97%)	⬇️
pkg/docker/manifest.go	57.50% <ø> (+3.50%)	⬆️
pkg/docker/digest.go	56.25% <60.91%> (-6.58%)	⬇️
pkg/docker/auth.go	60.46% <0.00%> (+1.55%)	⬆️
pkg/docker/registry.go	45.45% <0.00%> (+45.45%)	⬆️
pkg/docker/trust.go	52.72% <0.00%> (+52.72%)	⬆️

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[tigerinus]

This is needed due to google/go-containerregistry#377