Support CNB builder platform API 0.3

This commit adds support for Cloud Native Buildpacks builder platform
API 0.3, which is the latest platform API available currently. Support
for platform API 0.1 has been removed, adopting the policy of the pack
CLI to support the current platform API version and one version prior.

Fixes gh-20757

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/resources/org/springframework/boot/gradle/tasks/bundling/BootBuildImageIntegrationTests-buildsImageWithV2Builder.gradle

@@ -7,5 +7,5 @@ sourceCompatibility = '1.8'
 targetCompatibility = '1.8'
 
  bootBuildImage {
-	 builder = "cloudfoundry/cnb:bionic-platform-api-0.1"
+	 builder = "cloudfoundry/cnb:bionic-platform-api-0.2"
  }