Upgrade build to Gradle 7

Closes gh-572

gradle/dependency-management.gradle

@@ -1,38 +0,0 @@
-if (!project.hasProperty("springVersion")) {
-	ext.springVersion = "5.3.16"
-}
-
-if (!project.hasProperty("springSecurityVersion")) {
-	ext.springSecurityVersion = "5.5.5"
-}
-
-if (!project.hasProperty("reactorVersion")) {
-	ext.reactorVersion = "2020.0.16"
-}
-
-if (!project.hasProperty("locksDisabled")) {
-	dependencyLocking {
-		lockAllConfigurations()
-	}
-}
-
-dependencyManagement {
-	imports {
-		mavenBom "org.springframework:spring-framework-bom:$springVersion"
-		mavenBom "org.springframework.security:spring-security-bom:$springSecurityVersion"
-		mavenBom "io.projectreactor:reactor-bom:$reactorVersion"
-        mavenBom "com.fasterxml.jackson:jackson-bom:2.12.6"
-	}
-
-	dependencies {
-		dependency "com.nimbusds:nimbus-jose-jwt:9.10.1"
-		dependency "javax.servlet:javax.servlet-api:4.0.1"
-		dependency 'junit:junit:4.13.2'
-		dependency 'org.assertj:assertj-core:3.19.0'
-		dependency 'org.mockito:mockito-core:3.9.0'
-		dependency "com.squareup.okhttp3:mockwebserver:3.14.9"
-		dependency "com.squareup.okhttp3:okhttp:3.14.9"
-		dependency "com.jayway.jsonpath:json-path:2.5.0"
-		dependency "org.hsqldb:hsqldb:2.5.2"
-	}
-}

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-6.9-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.3-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists