Revert to Spring GraphQL 1.3.0-M1

Spring for GraphQL 1.3.0-M2 has been cancelled and 1.3.0-RC1 will be
released in time for Spring Boot 3.3.0-RC1 instead.

See gh-39895

spring-boot-project/spring-boot-dependencies/build.gradle

@@ -1847,7 +1847,7 @@ bom {
 			releaseNotes("https://github.com/spring-projects/spring-framework/releases/tag/v{version}")
 		}
 	}
-	library("Spring GraphQL", "1.3.0-SNAPSHOT") {
+	library("Spring GraphQL", "1.3.0-M1") {
 		considerSnapshots()
 		group("org.springframework.graphql") {
 			modules = [