Bump ch.qos.logback:logback-core from 1.3.14 to 1.3.15 in /src/server

Bumps [ch.qos.logback:logback-core](https://github.com/qos-ch/logback) from 1.3.14 to 1.3.15.
- [Commits](qos-ch/logback@v_1.3.14...v_1.3.15)

---
updated-dependencies:
- dependency-name: ch.qos.logback:logback-core
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

src/server/pom.xml

@@ -31,7 +31,7 @@
     <properties>
         <dropwizard.version>2.1.12</dropwizard.version>
         <jersey.version>2.35</jersey.version>
-        <logback.version>1.3.14</logback.version>
+        <logback.version>1.3.15</logback.version>
         <cxf.version>3.4.5</cxf.version>
         <shiro.version>1.13.0</shiro.version>
         <prometheus.version>0.12.0</prometheus.version>