build: Pin grpcio-tools to the gRPC v1.81.x train

The python client gRPC stubs are generated with grpcio-tools, which was
installed unpinned and floated to the newest PyPI release (1.82.x)
after the gRPC v1.81.1 third_party bump. The generated
grpc_service_pb2_grpc.py then asserted grpcio>=1.82.1 at import time,
while the runtime shipped an older grpcio — breaking every L0 test that
imports tritonclient.grpc. Pin grpcio-tools to 1.81.x so the generated
stubs track the same gRPC minor as the C++ library, keeping the whole
stack on one deterministic train.

Author: mc-nv

Dockerfile.sdk

@@ -83,7 +83,7 @@ RUN apt-get update && \
             software-properties-common \
             vim \
             wget && \
-    pip3 install --upgrade grpcio-tools cmake==4.0.3 auditwheel
+    pip3 install --upgrade "grpcio-tools>=1.81.1,<1.82" cmake==4.0.3 auditwheel
 
 ENV CMAKE_POLICY_MINIMUM_REQUIRED=3.5
 
@@ -182,7 +182,7 @@ RUN apt-get update && \
             python3-wheel \
             vim \
             wget && \
-    pip3 install "grpcio>=1.81.1" grpcio-tools && \
+    pip3 install "grpcio>=1.81.1,<1.82" "grpcio-tools>=1.81.1,<1.82" && \
     apt-get clean && \
     rm -rf /var/lib/apt/lists/* /var/cache/apt/archives/*;