Bump gson from 2.8.1 to 2.8.9

Bumps [gson](https://github.com/google/gson) from 2.8.1 to 2.8.9.
- [Release notes](https://github.com/google/gson/releases)
- [Changelog](https://github.com/google/gson/blob/master/CHANGELOG.md)
- [Commits](google/gson@gson-parent-2.8.1...gson-parent-2.8.9)

---
updated-dependencies:
- dependency-name: com.google.code.gson:gson
  dependency-type: direct:production
...

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

Author: dependabot[bot]

pom.xml

@@ -243,7 +243,7 @@
         <gson-fire-version>1.8.0</gson-fire-version>
         <swagger-core-version>1.5.15</swagger-core-version>
         <okhttp-version>2.7.5</okhttp-version>
-        <gson-version>2.8.1</gson-version>
+        <gson-version>2.8.9</gson-version>
             <threetenbp-version>1.3.5</threetenbp-version>
         <maven-plugin-version>1.0.0</maven-plugin-version>
         <junit-version>4.12</junit-version>