Bump com.microsoft.graph:microsoft-graph in /msal-obo-sample

Bumps [com.microsoft.graph:microsoft-graph](https://github.com/microsoftgraph/msgraph-sdk-java) from 5.5.0 to 6.28.0.
- [Release notes](https://github.com/microsoftgraph/msgraph-sdk-java/releases)
- [Changelog](https://github.com/microsoftgraph/msgraph-sdk-java/blob/main/CHANGELOG.md)
- [Commits](microsoftgraph/msgraph-sdk-java@v5.5.0...v6.28.0)

---
updated-dependencies:
- dependency-name: com.microsoft.graph:microsoft-graph
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

msal-obo-sample/pom.xml

@@ -29,7 +29,7 @@
         <dependency>
             <groupId>com.microsoft.graph</groupId>
             <artifactId>microsoft-graph</artifactId>
-            <version>5.5.0</version>
+            <version>6.28.0</version>
         </dependency>
         <!-- Spring 3 dependencies -->
         <dependency>