Update spring-batch-db-examples and spring-batch-file-examples to Spring Batch 6

## Description

This issue tracks the work to update the following modules to Spring Batch 6:

- spring-batch-db-examples
- spring-batch-file-examples

## Context

This request was made by @igorcampos-dev in PR #124.

## Reference

- Pull Request: https://github.com/igorcampos-dev/spring-integrations-examples/pull/124