renovatebot(deps): update dependency com.splunk.logging:splunk-library-javalogging to v1.8.0
renovatebot(deps): update dependency com.splunk.logging:splunk-library-javalogging to v1.8.0

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [com.splunk.logging:splunk-library-javalogging](http://dev.splunk.com/goto/sdk-slj) ([source](https://togithub.com/splunk/splunk-library-javalogging)) | minor | `1.7.3` -> `1.8.0` |

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### Release Notes

<details>
<summary>splunk/splunk-library-javalogging</summary>

### [`v1.8.0`](https://togithub.com/splunk/splunk-library-javalogging/blob/master/CHANGELOG.md#Version-180)

-   Update JSON serialization- message property should not be encoded as a string
-   Changed underlying HTTP client to OkHttp. This change should decrease memory
    usage and increase performance.
-   Updated Gradle build plugins to latest versions

</details>

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This PR has been generated by [Renovate Bot](https://togithub.com/renovatebot/renovate).
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