chore(deps): bump com.azure:azure-identity in /backend

Bumps [com.azure:azure-identity](https://github.com/Azure/azure-sdk-for-java) from 1.18.1 to 1.18.4.
- [Release notes](https://github.com/Azure/azure-sdk-for-java/releases)
- [Commits](Azure/azure-sdk-for-java@azure-identity_1.18.1...com.azure+azure-identity_1.18.4)

---
updated-dependencies:
- dependency-name: com.azure:azure-identity
  dependency-version: 1.18.4
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

backend/pom.xml

@@ -198,7 +198,7 @@
         <dependency>
             <groupId>com.azure</groupId>
             <artifactId>azure-identity</artifactId>
-            <version>1.18.1</version>
+            <version>1.18.4</version>
         </dependency>
 
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