Unit tests: Upgrade alpine to using the latest version tag

[pacostas]

Describe the Enhancement

Unit tests currently use alpine 3.15.4 on 3.19 versions https://github.com/search?q=repo%3Apaketo-buildpacks%2Fjam%20alpine%3A&type=code . It is preferable to always use the latest tag instead of sticking to a specific version so as not to have to upgrade the alpine version manually.

Possible Solution

• instead of matching the /etc/os-release match the /usr/lib/os-release
• Some tests are getting skipped due to some files having changed location on the latest alpine image. Make the tests error instead of skipping, so we can immediately be informed which tests are not running, as skipping tests reduce the test coverage.