Upgrade to Picocli 3.0.0

[kakawait]

• [ ] Rework version and help display https://github.com/remkop/picocli/issues/162 https://github.com/remkop/picocli/issues/145
• [ ] Consider https://github.com/remkop/picocli/issues/157 could be useful
• [x] Support subcommand https://github.com/remkop/picocli/issues/152 (see #12)

[bobtiernay-okta]

Any chance of upgrading to 3.0.0?

[kakawait]

If released yes i will directly upgrade to latest.

[kakawait]

@bobtiernay-okta I just created a new branch picocli-3.0.0 where I upgrade picocli dep to 3.0.0-beta-1 (latest version in maven central, I will upgrade to beta-2 as soon as is will be available on maven central)

In addition I pushed the artifact with version

<dependency>
    <groupId>com.kakawait</groupId>
    <artifactId>picocli-spring-boot-starter</artifactId>
    <version>1.0.0-alpha-1</version>
</dependency>

Be careful I just pushed can take some time before available on maven central

Why alpha?

For two main reasons:

1. Not heavily tested
2. Not specific integration (in order to take advantage of new things/features), just upgraded deps and fix compilation/runtime issues

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Please if you have any issue (if you have time to test) report it.

Currently I'm working on other of my open sourced starter to get Spring boot 2 support, then I will focus on that starter