build: Bump com.vonage:server-sdk to 8.20.1 (#32)

Bumps [com.vonage:server-sdk](https://github.com/Vonage/vonage-java-sdk) from 8.20.0 to 8.20.1.
- [Release notes](https://github.com/Vonage/vonage-java-sdk/releases)
- [Changelog](https://github.com/Vonage/vonage-java-sdk/blob/main/CHANGELOG.md)
- [Commits](Vonage/vonage-java-sdk@v8.20.0...v8.20.1)

---
updated-dependencies:
- dependency-name: com.vonage:server-sdk
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Author: dependabot[bot]

pom.xml

@@ -55,7 +55,7 @@
     <dependency>
       <groupId>com.vonage</groupId>
       <artifactId>server-sdk</artifactId>
-      <version>8.20.0</version>
+      <version>8.20.1</version>
     </dependency>
     <dependency>
       <groupId>org.jetbrains.kotlin</groupId>