deps: update dependency com.google.code.gson:gson to v2.8.7 (googleap…

…is#461)

[![WhiteSource Renovate](https://app.renovatebot.com/images/banner.svg)](https://renovatebot.com)

This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| com.google.code.gson:gson | `2.8.6` -> `2.8.7` | [![age](https://badges.renovateapi.com/packages/maven/com.google.code.gson:gson/2.8.7/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/maven/com.google.code.gson:gson/2.8.7/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/maven/com.google.code.gson:gson/2.8.7/compatibility-slim/2.8.6)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/maven/com.google.code.gson:gson/2.8.7/confidence-slim/2.8.6)](https://docs.renovatebot.com/merge-confidence/) |

---

### Configuration

📅 **Schedule**: At any time (no schedule defined).

🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied.

♻️ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about this update again.

---

 - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check this box.

---

This PR has been generated by [WhiteSource Renovate](https://renovate.whitesourcesoftware.com). View repository job log [here](https://app.renovatebot.com/dashboard#github/googleapis/java-core).

pom.xml

@@ -170,7 +170,7 @@
     <threetenbp.version>1.5.1</threetenbp.version>
     <objenesis.version>2.6</objenesis.version>
     <errorprone.version>2.7.1</errorprone.version>
-    <gson.version>2.8.6</gson.version>
+    <gson.version>2.8.7</gson.version>
   </properties>
 
   <dependencyManagement>