Use resolved dependency versions for published POMs

This commit ensures that Gradle publications are using resolved
dependency versions for Maven publications (i.e. POMs). This is useful
since we're using the Spring dependency management plugin and we can't
rely on declared dependency versions only.

See gh-23282

gradle/publications.gradle

@@ -36,6 +36,14 @@ publishing {
 					url = "https://github.com/spring-projects/spring-framework/issues"
 				}
 			}
+			versionMapping {
+				usage('java-api') {
+					fromResolutionResult()
+				}
+				usage('java-runtime') {
+					fromResolutionResult()
+				}
+			}
 		}
 	}
 }