Update SNAPSHOT version to v2.15.0

Author: github-actions[bot]

pom.xml

@@ -18,7 +18,7 @@
     </parent>
 
     <artifactId>powsybl-single-line-diagram-server</artifactId>
-    <version>2.14.0-SNAPSHOT</version>
+    <version>2.15.0-SNAPSHOT</version>
 
     <packaging>jar</packaging>
     <name>Single line diagram server</name>