Bump mina-core from 2.1.4 to 2.1.5 in /quickfixj-core (#433)

Bumps [mina-core](https://github.com/apache/mina) from 2.1.4 to 2.1.5.
- [Release notes](https://github.com/apache/mina/releases)
- [Commits](apache/mina@2.1.4...2.1.5)

---
updated-dependencies:
- dependency-name: org.apache.mina:mina-core
  dependency-type: direct:production
...

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quickfixj-core/pom.xml

@@ -59,7 +59,7 @@
         <dependency>
             <groupId>org.apache.mina</groupId>
             <artifactId>mina-core</artifactId>
-            <version>2.1.4</version>
+            <version>2.1.5</version>
         </dependency>
         <dependency>
             <groupId>org.slf4j</groupId>