fix(bug): fix #117 handle blank image_tag_alias

[dekobon]

When image_tag_alias is blank, a custom KIC image is not loaded because image_tag_alias may be present in repository_url but just a blank string. This change consolidates the logic into a single function and adds a check for a blank string.

Proposed changes

This PR fixes #117 and updates to the 1.3 tag for the Bank of Sirius app.

Checklist

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• I have written my commit messages in the Conventional Commits format.
• I have read the CONTRIBUTING doc
• I have added tests (when possible) that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto master
• I will ensure my PR is targeting the master branch and pulling from my branch from my own fork

[qdzlug]

Looks good to me.