Update java version

[jenarp]

Dear Team (especially @mfbieber, @basseur, @bonndan, @Matthimatiker),

if you desire to use the java, spring, etc. updated AoC version please have a look if everything is correct.

Regarding the frontend I got into trouble showing the results (answer text) on the Cards. They were not visible anymore after changes in AdventOfCodeController.java (DayModel).
Robert and I adjusted the changes in CardTemplate.js. Not sure if this is a clean fix.

[jenarp]

Hi all,
unfortunately the deployment on Heroku failed. I think something is still phishy about gradle or java build versions... :-(

[MatthiasMolitor]

@jenarp Has the problem been resolved?

[jenarp]

@Matthimatiker Due to Heroku I tried a lot of things, thus I decided this is not worth a Pull Request at the moment. At the moment app is running locally but deployment with Heroku ist still an issue.

[bonndan]

We have discussed the option of deploying Docker images instead.

[MatthiasMolitor]

As the app runs locally with Java 17 and Heroku claims to support Java 17 (https://devcenter.heroku.com/articles/java-support), it might also be possible to switch to a plain Java buildpack (instead of the Gradle buildpack) and run gradlew.

[mfbieber]

@jenarp: could you reopen this PR so that I could check out the logs at Heroku? I would suggest trying Matthias' suggestion!