Integrate dependabot with download spring-boot and micronaut pom

[mshima]

Overview of the feature request

Download Micronaut and Spring Boot pom and add to dependabot PR.
Like in React Native: https://github.com/jhipster/generator-jhipster-react-native/blob/4ca268c4640f1f9d6a8be7748f5a75b37cb7be03/.github/workflows/merge.yml#L29

Motivation for or Use Case

Related issues or PR

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[github-actions]

This issue is stale because it has been open for too long without any activity.
Due to the moving nature of jhipster generated application, bugs can become invalid.
If this issue still applies please comment otherwise it will be closed in 7 days