chore(deps): update dependency com.google.cloud:google-cloud-document-ai to v2.6.0 (#861)

[![Mend 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.cloud:google-cloud-document-ai](https://togithub.com/googleapis/java-document-ai) | `2.5.2` -> `2.6.0` | [![age](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-document-ai/2.6.0/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-document-ai/2.6.0/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-document-ai/2.6.0/compatibility-slim/2.5.2)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-document-ai/2.6.0/confidence-slim/2.5.2)](https://docs.renovatebot.com/merge-confidence/) |

---

### Configuration

📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

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

♻ **Rebasing**: Renovate will not automatically rebase this PR, because other commits have been found.

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

---

 - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, click this checkbox. ⚠ **Warning**: custom changes will be lost.

---

This PR has been generated by [Mend Renovate](https://www.mend.io/free-developer-tools/renovate/). View repository job log [here](https://app.renovatebot.com/dashboard#github/googleapis/java-document-ai).
<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiIzMi4xMzUuMSIsInVwZGF0ZWRJblZlciI6IjMyLjEzNS4xIn0=-->

Author: renovate-bot

document-ai/snippets/pom.xml

@@ -41,7 +41,7 @@
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>google-cloud-document-ai</artifactId>
-      <version>2.5.2</version>
+      <version>2.6.0</version>
     </dependency>
     <!-- [END documentai_install_with_bom] -->
     <dependency>