Align Kotlin dependency on Spring Framework 5.3.x

Prior to this commit, spring-graphql would depend on Kotlin 1.6, which
is not in line with Spring Framework 5.3.x requirements. This commit
realigns our dependency management on Kotlin 1.5.x.

Also, this commit configures the build to not publish a kotlin-stdlib
runtime dependency in our POM.

Closes gh-265

build.gradle

@@ -1,6 +1,6 @@
 plugins {
 	id 'io.spring.dependency-management' version '1.0.11.RELEASE'
-	id 'org.jetbrains.kotlin.jvm' version '1.6.0' apply false
+	id 'org.jetbrains.kotlin.jvm' version '1.5.32' apply false
 }
 
 ext {
@@ -63,7 +63,7 @@ configure(moduleProjects) {
 			mavenBom "org.springframework.data:spring-data-bom:2021.1.0"
 			mavenBom "org.springframework.security:spring-security-bom:5.6.0"
 			mavenBom "com.querydsl:querydsl-bom:5.0.0"
-			mavenBom "org.jetbrains.kotlin:kotlin-bom:1.6.0"
+			mavenBom "org.jetbrains.kotlin:kotlin-bom:1.5.32"
 			mavenBom "org.jetbrains.kotlinx:kotlinx-coroutines-bom:1.5.2"
 			mavenBom "org.junit:junit-bom:5.8.1"
 			mavenBom "org.testcontainers:testcontainers-bom:1.16.2"

gradle.properties

@@ -4,3 +4,5 @@ org.gradle.caching=true
 org.gradle.daemon=true
 org.gradle.parallel=true
 org.gradle.jvmargs=-Dfile.encoding=UTF-8
+
+kotlin.stdlib.default.dependency=false

spring-graphql/build.gradle

@@ -19,8 +19,8 @@ dependencies {
 	compileOnly 'org.springframework.data:spring-data-commons'
 
 	compileOnly 'com.google.code.findbugs:jsr305'
-	compileOnly 'org.jetbrains.kotlinx:kotlinx-coroutines-core'
 	compileOnly 'org.jetbrains.kotlin:kotlin-stdlib'
+	compileOnly 'org.jetbrains.kotlinx:kotlinx-coroutines-core'
 
 	compileOnly 'javax.validation:validation-api'
 
@@ -54,7 +54,6 @@ dependencies {
 
 	testRuntimeOnly 'org.apache.logging.log4j:log4j-core'
 	testRuntimeOnly 'org.apache.logging.log4j:log4j-slf4j-impl'
-	implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8"
 }
 
 test {