Dockerfile is update with the latest bazelisk version and a new env varibale is added in order to download the rigth bazel version

Change-Id: I28ff28d6c5f27f9be54dc96a0042ff12a0597125
diff --git a/Dockerfile b/Dockerfile
index 6a168c5..22479d9 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -33,10 +33,11 @@
     curl \
     unzip
 RUN apt-get update && apt-get install -y ${BUILD_DEPS}
+ENV BAZELISK_BASE_URL="https://releases.bazel.build/6.0.0/rolling"
 
 # Install Bazelisk, which will download the version of bazel specified in
 # .bazelversion
-RUN curl -L -o bazelisk https://github.com/bazelbuild/bazelisk/releases/download/v1.11.0/bazelisk-linux-amd64
+RUN curl -L -o bazelisk https://github.com/bazelbuild/bazelisk/releases/download/v1.19.0/bazelisk-linux-amd64
 RUN chmod +x bazelisk && mv bazelisk /usr/bin
 
 # Build-stage environment variables
@@ -99,4 +100,4 @@
 
 # Run ONOS
 ENTRYPOINT ["./bin/onos-service"]
-CMD ["server"]
+CMD ["server"]
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