Upgrade swagger-annotations 1.6.8 -> 1.6.9 (#352)

See:
- https://github.com/swagger-api/swagger-core/releases/tag/v1.6.9
- swagger-api/swagger-core@v1.6.8...v1.6.9

pom.xml

@@ -315,7 +315,7 @@
             <dependency>
                 <groupId>io.swagger</groupId>
                 <artifactId>swagger-annotations</artifactId>
-                <version>1.6.8</version>
+                <version>1.6.9</version>
             </dependency>
             <dependency>
                 <groupId>io.swagger.core.v3</groupId>