Bump azure-identity from 1.16.1 to 1.18.0 in /stix_shifter

Bumps [azure-identity](https://github.com/Azure/azure-sdk-for-python) from 1.16.1 to 1.18.0.
- [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-identity_1.16.1...azure-identity_1.18.0)

---
updated-dependencies:
- dependency-name: azure-identity
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

stix_shifter/requirements.txt

@@ -5,7 +5,7 @@ antlr4-python3-runtime==4.8
 asyncio==3.4.3
 asynctest==0.13.0
 attrs==23.1.0
-azure-identity==1.16.1
+azure-identity==1.18.0
 colorlog==6.8.2
 flask==3.0.0
 flatten_json==0.1.14