Start building against Spring Plugin 2.0.0.M1 snapshots

See gh-15940

spring-boot-project/spring-boot-dependencies/pom.xml

@@ -172,7 +172,7 @@
 		<spring-integration.version>5.1.3.BUILD-SNAPSHOT</spring-integration.version>
 		<spring-kafka.version>2.2.4.BUILD-SNAPSHOT</spring-kafka.version>
 		<spring-ldap.version>2.3.2.RELEASE</spring-ldap.version>
-		<spring-plugin.version>1.2.0.RELEASE</spring-plugin.version>
+		<spring-plugin.version>2.0.0.BUILD-SNAPSHOT</spring-plugin.version>
 		<spring-restdocs.version>2.0.3.RELEASE</spring-restdocs.version>
 		<spring-retry.version>1.2.4.RELEASE</spring-retry.version>
 		<spring-security.version>5.1.4.BUILD-SNAPSHOT</spring-security.version>