Bump org.springframework.boot from 2.4.2 to 2.4.3 in /java/backend (#193

)

Bumps [org.springframework.boot](https://github.com/spring-projects/spring-boot) from 2.4.2 to 2.4.3.
- [Release notes](https://github.com/spring-projects/spring-boot/releases)
- [Commits](spring-projects/spring-boot@v2.4.2...v2.4.3)

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

java/backend/build.gradle

@@ -1,6 +1,6 @@
 plugins {
     id 'java'
-    id 'org.springframework.boot' version '2.4.2'
+    id 'org.springframework.boot' version '2.4.3'
     id 'com.revolut.jooq-docker' version '0.3.6'
     id 'groovy'
     id 'uk.gov.hmcts.java' version '0.12.4'