Bump gson from 2.1 to 2.8.9

Bumps [gson](https://github.com/google/gson) from 2.1 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-2.1...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]>

pom.xml

@@ -412,7 +412,7 @@
         <fasterxml.jackson.version>2.10.3</fasterxml.jackson.version>
         <carbon.kernel.version>4.6.0</carbon.kernel.version>
         <fasterxml.jackson.databind.version>2.10.3</fasterxml.jackson.databind.version>
-        <gson.version>2.1</gson.version>
+        <gson.version>2.8.9</gson.version>
         <carbon.p2.plugin.version>1.5.3</carbon.p2.plugin.version>
         <project.version>1.0.0-SNAPSHOT</project.version>
         <imp.package.version.osgi.framework>[1.6.0, 2.0.0)</imp.package.version.osgi.framework>
@@ -431,7 +431,7 @@
         <io.swagger.codegen.version>2.4.11</io.swagger.codegen.version>
         <identity.auth.rest.version>1.4.0</identity.auth.rest.version>
         <carbon.apimgt.imp.pkg.version>[6.7.0, 10.0.0)</carbon.apimgt.imp.pkg.version>
-        <com.google.code.gson.version>2.8.5</com.google.code.gson.version>
+        <com.google.code.gson.version>2.8.9</com.google.code.gson.version>
         <junit.version>4.12</junit.version>
         <powermock.version>1.7.4</powermock.version>
         <mockito.all.version>1.10.19</mockito.all.version>