Bump org.springframework.boot from 3.5.7 to 4.0.0 in /perf-tests

Bumps org.springframework.boot from 3.5.7 to 4.0.0.

---
updated-dependencies:
- dependency-name: org.springframework.boot
  dependency-version: 4.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

perf-tests/build.gradle

@@ -1,6 +1,6 @@
 plugins {
   id 'java'
-  id 'org.springframework.boot' version '3.5.7'
+  id 'org.springframework.boot' version '4.0.0'
   id 'io.spring.dependency-management' version '1.1.7'
 }