add docker login action

[shreyas-badiger]

Docker login action was missing.

Error: buildx failed with: ERROR: failed to solve: failed to push master: 
failed to authorize: failed to fetch oauth token: 

unexpected status from GET request to https://auth.docker.io/token?scope=repository%3Alibrary%2Fmaster%3Apull%2Cpush&service=registry.docker.io: 
401 Unauthorized

https://github.com/keikoproj/upgrade-manager/actions/runs/5536644181/jobs/10104571473

[codecov]

Codecov Report

Merging #354 (d02f36d) into master (952b2df) will not change coverage.
The diff coverage is n/a.

❗ Current head d02f36d differs from pull request most recent head 9a61508. Consider uploading reports for the commit 9a61508 to get more accurate results

@@           Coverage Diff           @@
##           master     #354   +/-   ##
=======================================
  Coverage   45.17%   45.17%           
=======================================
  Files           7        7           
  Lines         757      757           
=======================================
  Hits          342      342           
  Misses        376      376           
  Partials       39       39           

Flag	Coverage Δ
unittests	45.17% <ø> (ø)

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