Update Dockerfile

typo on image ref

Dockerfile

@@ -21,7 +21,7 @@ CMD ["python3", "example_browserclient/server.py"]
 
 # --------------------------------------------
 
-FROM ubuntu22.04 as cpu
+FROM ubuntu:22.04 as cpu
 
 WORKDIR /app
 
@@ -36,4 +36,4 @@ RUN pip3 install -r /app/requirements.txt
 EXPOSE 9001
 ENV PYTHONPATH "${PYTHONPATH}:/app"
 RUN export PYTHONPATH="${PYTHONPATH}:/app"
-CMD ["python3", "example_browserclient/server.py"]
+CMD ["python3", "example_browserclient/server.py"]