chore: removing digestabot update workflow

[btlghrants]

Description

We're refocusing on having Dependabot update image digests across the Pepr project so no need for this job anymore.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Other (security config, docs update, etc)

Checklist before merging

• Unit, Journey, E2E Tests, docs, adr added or updated as needed
• Contributor Guide Steps followed

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.52%. Comparing base (094fa1c) to head (63774f0).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1686   +/-   ##
=======================================
  Coverage   79.52%   79.52%           
=======================================
  Files          48       48           
  Lines        2090     2090           
  Branches      430      460   +30     
=======================================
  Hits         1662     1662           
  Misses        426      426           
  Partials        2        2           

[samayer12]

Approved, discussed sync