Pin maven-deploy-plugin version in spring-cloud-dependencies-parent

spring-cloud-dependencies-parent has no parent POM and does not manage the
maven-deploy-plugin, so with Maven < 3.9 it falls back to the core default
maven-deploy-plugin 2.7. That version predates the
altSnapshotDeploymentRepository parameter (added in 2.8), so any deploy that
relies on that flag is silently ignored for this module and it falls back to
the repository declared in its own distributionManagement.

Pin the plugin to 3.1.4 to match the version used by the spring-cloud-build
root POM so the module honors the alternate deployment repository flags.

Signed-off-by: Ryan Baxter <rbaxter85@gmail.com>

spring-cloud-dependencies-parent/pom.xml

@@ -71,6 +71,7 @@
 	<properties>
 		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 		<central-publishing-maven-plugin.version>0.9.0</central-publishing-maven-plugin.version>
+		<maven-deploy-plugin.version>3.1.4</maven-deploy-plugin.version>
 	</properties>
 	<distributionManagement>
 		<downloadUrl>https://github.com/spring-cloud</downloadUrl>
@@ -208,6 +209,11 @@
 	<build>
 		<pluginManagement>
 			<plugins>
+				<plugin>
+					<groupId>org.apache.maven.plugins</groupId>
+					<artifactId>maven-deploy-plugin</artifactId>
+					<version>${maven-deploy-plugin.version}</version>
+				</plugin>
 				<plugin>
 					<groupId>org.apache.maven.plugins</groupId>
 					<artifactId>maven-enforcer-plugin</artifactId>