test(spring): add Spring Boot 2.7 and 3.x test applications

[andrewazores]

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Fixes: #19

Description of the change:

This change allows an environment variable to be configured so that...

Motivation for the change:

This change is helpful because users may want to...

How to manually test:

1. Run CRYOSTAT_IMAGE=quay.io... bash smoketest.bash...
2. ...