Update spring-boot version to 2.7.0

[DanielFran]

Fixes #18510
Related #18071

Depends on jhipster/jhipster-bom#790

Issues identified:

• Group ID of r2dbc-postgresql, the driver for PostgreSQL, has changed from io.r2dbc to org.postgresql
• H2 liquibase script not working (waiting for liquibase-hibernate 4.11)
• R2dbc driver for mysql excluded (dev.miku:r2dbc-mysql): suggested to use r2dbc-mariadb instead

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[CLAassistant]

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[mraible]

@DanielFran Anything I can do to help with this?

[DanielFran]

@mraible I was working on H2 issues, waiting for liquibase-hibernate 4.11 release that should fix those issues
So if you have time to test r2dbc MYSQL with mariadb dependency it will help...

Note: Issue list is available on PR description.