Fix image-tag input

[lakkeger]

Motivation

Image tag causing currently more confusion than what it solves, namely:

• cli fails back to 3.2.0 if default pip version used
• correct image version downloaded but LS not starting that

Changes

• pip upgrade
• new version test pipeline
• image_name env var used to control image version
• image-tag parameter populates image_name if the env variable missing

[github-actions]

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