[docker-ptf]: Updating Python-based GNMI client (#6216)

Upgrading the reference for the Python GNMI tool repository. The commit for the new payload

Co-authored-by: Murat Acikgoz <muacikgo@microsoft.com>

dockers/docker-ptf/Dockerfile.j2

@@ -142,7 +142,7 @@ RUN mkdir -p /var/log/supervisor
 # Install Python-based GNMI client
 RUN git clone https://github.com/lguohan/gnxi.git \
     && cd gnxi \
-    && git checkout d01b36e \
+    && git checkout 53901ab \
     && cd gnmi_cli_py \
     && pip install -r requirements.txt