Add milestone repository to dependencies.

Author: OlgaMaciaszek

spring-cloud-vault-dependencies/pom.xml

@@ -131,6 +131,14 @@
 				<enabled>true</enabled>
 			</snapshots>
 		</repository>
+		<repository>
+			<id>spring-milestones</id>
+			<name>Spring Milestones</name>
+			<url>https://repo.spring.io/milestone</url>
+			<snapshots>
+				<enabled>false</enabled>
+			</snapshots>
+		</repository>
 	</repositories>
 
 </project>