fix: cmd/suggestion/nas/darts/v1beta1/requirements.txt to reduce vulnerabilities

The following vulnerabilities are fixed by pinning transitive dependencies:
- https://snyk.io/vuln/SNYK-PYTHON-PROTOBUF-10364902

Author: snyk-bot

cmd/suggestion/nas/darts/v1beta1/requirements.txt

@@ -1,4 +1,4 @@
 grpcio==1.41.1
-protobuf==3.19.1
+protobuf==4.25.8
 googleapis-common-protos==1.6.0
 cython>=0.29.24