fix(deps): update dependency org.openapitools:openapi-generator to v7.7.0 (#647)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
|
[org.openapitools:openapi-generator](https://togithub.com/openapitools/openapi-generator)
| `7.6.0` -> `7.7.0` |
[![age](https://developer.mend.io/api/mc/badges/age/maven/org.openapitools:openapi-generator/7.7.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![adoption](https://developer.mend.io/api/mc/badges/adoption/maven/org.openapitools:openapi-generator/7.7.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![passing](https://developer.mend.io/api/mc/badges/compatibility/maven/org.openapitools:openapi-generator/7.6.0/7.7.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![confidence](https://developer.mend.io/api/mc/badges/confidence/maven/org.openapitools:openapi-generator/7.6.0/7.7.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|

---

### Release Notes

<details>
<summary>openapitools/openapi-generator
(org.openapitools:openapi-generator)</summary>

###
[`v7.7.0`](https://togithub.com/OpenAPITools/openapi-generator/releases/tag/v7.7.0):
released

v7.7.0 stable release comes with 140+ enhancements, bug fixes. Once
again thank you for all the awesome contributions from the community.

For a full list of changes, please refer to the ["Pull
Request"](https://togithub.com/OpenAPITools/openapi-generator/pulls?q=is%3Amerged+is%3Apr+milestone%3A7.7.0+)
tab.

</details>

---

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generator/pom.xml

@@ -126,7 +126,7 @@
     </dependencies>
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-        <openapi-generator-version>7.6.0</openapi-generator-version>
+        <openapi-generator-version>7.7.0</openapi-generator-version>
         <maven-plugin-version>1.0.0</maven-plugin-version>
         <junit-version>4.13.2</junit-version>
     </properties>