Add confluent debian repo for performance benchmark

Author: milindl

.semaphore/semaphore.yml

@@ -123,6 +123,10 @@ blocks:
           value: "0.02"
       prologue:
         commands:
+          - wget -qO - https://packages.confluent.io/deb/7.7/archive.key | sudo apt-key add -
+          - sudo add-apt-repository "deb https://packages.confluent.io/clients/deb $(lsb_release -cs) main"
+          - sudo apt-get update
+          - sudo apt-get install -y build-essential gcc g++ make python3
           - sudo apt-get install -y librdkafka-dev bc
           - export CKJS_LINKING=dynamic
           - export BUILD_LIBRDKAFKA=0