Update dependency org.springframework.cloud:spring-cloud-starter-openfeign to v4

Author: renovate[bot]

build.gradle

@@ -242,7 +242,7 @@ dependencies {
   implementation 'org.springframework.boot:spring-boot-starter-actuator'
   implementation 'org.springframework.boot:spring-boot-configuration-processor'
   implementation 'org.springframework.boot:spring-boot-starter-data-jpa'
-  implementation group: 'org.springframework.cloud', name: 'spring-cloud-starter-openfeign', version: '3.1.8'
+  implementation group: 'org.springframework.cloud', name: 'spring-cloud-starter-openfeign', version: '4.2.1'
   implementation 'org.springframework.retry:spring-retry'
   implementation group: 'org.testng', name: 'testng', version: '7.11.0'
   implementation group: 'uk.gov.service.notify', name: 'notifications-java-client', version: '5.2.1-RELEASE'