Bump logback-classic to 1.3.15

See https://logback.qos.ch/news.html#1.3.15

Author: sbesson

pom.xml

@@ -168,7 +168,7 @@
     <dependency>
       <groupId>ch.qos.logback</groupId>
       <artifactId>logback-classic</artifactId>
-      <version>1.3.14</version>
+      <version>1.3.15</version>
       <optional>true</optional>
     </dependency>
     <dependency>