Bump logback-core from 1.0.13 to 1.2.0 in /websocket/atmosphere-chat

Bumps logback-core from 1.0.13 to 1.2.0.

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

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Author: dependabot[bot]

websocket/atmosphere-chat/pom.xml

@@ -30,7 +30,7 @@
         <dependency>
             <groupId>ch.qos.logback</groupId>
             <artifactId>logback-core</artifactId>
-            <version>1.0.13</version>
+            <version>1.2.0</version>
         </dependency>
         <dependency>
             <groupId>org.atmosphere</groupId>