Update github.com/docker/distribution dependency to 2.8.1

[chrisdoherty4]

Update github.com/docker/distribution dep to 2.8.1. I built the artifacts and found no download issues. I also took the liberty of tidying the go.sum with go mod tidy.

See #593 and distribution/distribution#3590

[codecov]

Codecov Report

Merging #594 (d65c7cd) into main (e053ada) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #594   +/-   ##
=======================================
  Coverage   43.41%   43.41%           
=======================================
  Files          52       51    -1     
  Lines        3107     3107           
=======================================
  Hits         1349     1349           
  Misses       1673     1673           
  Partials       85       85           

Impacted Files	Coverage Δ
pkg/apis/core/v1alpha1/hardware_methods.go	100.00% <0.00%> (ø)
pkg/apis/core/v1alpha1/template_types.go

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[chrisdoherty4]

@mmlb