Fix parent gpg signing

spring-cloud-starter-parent/pom.xml

@@ -121,6 +121,23 @@
 		</profile>
 		<profile>
 			<id>central</id>
+			<build>
+				<plugins>
+					<plugin>
+						<groupId>org.apache.maven.plugins</groupId>
+						<artifactId>maven-gpg-plugin</artifactId>
+						<executions>
+							<execution>
+								<id>sign-artifacts</id>
+								<phase>verify</phase>
+								<goals>
+									<goal>sign</goal>
+								</goals>
+							</execution>
+						</executions>
+					</plugin>
+				</plugins>
+			</build>
 			<distributionManagement>
 				<snapshotRepository>
 					<id>sonatype-nexus-snapshots</id>