Update azure-keyvault-secrets requirement in /code

Updates the requirements on [azure-keyvault-secrets](https://github.com/Azure/azure-sdk-for-python) to permit the latest version.
- [Release notes](https://github.com/Azure/azure-sdk-for-python/releases)
- [Changelog](https://github.com/Azure/azure-sdk-for-python/blob/main/doc/esrp_release.md)
- [Commits](Azure/azure-sdk-for-python@azure-keyvault-secrets_4.4.0b1...azure-keyvault-secrets_4.8.0)

---
updated-dependencies:
- dependency-name: azure-keyvault-secrets
  dependency-type: direct:production
...

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

Author: dependabot[bot]

code/backend/requirements.txt

@@ -21,4 +21,4 @@ azure-search-documents==11.4.0
 opencensus-ext-azure==1.1.13
 pandas==2.2.0
 python-docx==1.1.0
-azure-keyvault-secrets==4.4.*
+azure-keyvault-secrets==4.8.*

code/requirements.txt

@@ -24,4 +24,4 @@ azure-search-documents==11.4.0
 opencensus-ext-azure==1.1.13
 azure-ai-contentsafety==1.0.0
 python-docx==1.1.0
-azure-keyvault-secrets==4.4.*
+azure-keyvault-secrets==4.8.*