Bump swagger-core from 2.1.8 to 2.1.9 (#69)

Bumps [swagger-core](https://github.com/swagger-api/swagger-core) from 2.1.8 to 2.1.9.
- [Release notes](https://github.com/swagger-api/swagger-core/releases)
- [Commits](swagger-api/swagger-core@v2.1.8...v2.1.9)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

spotify-web-api-generator-open-api/pom.xml

@@ -20,7 +20,7 @@
     <url>https://github.com/sonallux/spotify-web-api</url>
 
     <properties>
-        <swagger-core.version>2.1.8</swagger-core.version>
+        <swagger-core.version>2.1.9</swagger-core.version>
         <swagger-parser.version>2.0.25</swagger-parser.version>
         <json-schema-validator.version>2.2.14</json-schema-validator.version>
     </properties>