upgrade springboot to 2.5.4

[backwind1233]

The dependency version in azure-spring-boot-samples is a little older,

  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.5.0</version> 
  </parent>

the version(2.5.0) is not compatible with azure-spring-boot-bom:3.9.0,
upgrade spring-boot-starter-parent to version 2.5.4, which is compatible with azure-spring-boot-bom:3.9.0,

---

refer to: #61, which introduced azure-spring-boot-bom:3.9.0.

[chenrujun]

LGTM.

[chenrujun]

LGTM.