Upgrade to Spring Boot 3.1.0 (halo-dev#3996)

#### What type of PR is this?

/kind cleanup
/area core
/milestone 2.6.x

#### What this PR does / why we need it:

Upgrade to Spring Boot 3.1.0, please refer to <https://github.com/spring-projects/spring-boot/releases/tag/v3.1.0>.

#### Does this PR introduce a user-facing change?

```release-note
升级 Spring Boot 至 3.1.0
```

application/build.gradle

@@ -1,5 +1,5 @@
 plugins {
-    id 'org.springframework.boot' version '3.1.0-RC2'
+    id 'org.springframework.boot' version '3.1.0'
     id 'io.spring.dependency-management' version '1.1.0'
     id "com.gorylenko.gradle-git-properties" version "2.3.2"
     id "checkstyle"

platform/application/build.gradle

@@ -1,7 +1,7 @@
 import org.springframework.boot.gradle.plugin.SpringBootPlugin
 
 plugins {
-    id 'org.springframework.boot' version '3.1.0-RC2' apply false
+    id 'org.springframework.boot' version '3.1.0' apply false
     id 'java-platform'
     id 'halo.publish'
     id 'signing'