COMP: Run apt-get update in Linux Azure build

To address missing packages in python3-venv install.

Author: thewtex

Utilities/Testing/azure-pipelines.yml

@@ -16,6 +16,7 @@ jobs:
         git clone -b dashboard --single-branch https://github.com/InsightSoftwareConsortium/ITKExamples.git ITKExamples-dashboard
 
         sudo pip3 install ninja
+        sudo apt-get update
         sudo apt-get install -y python3-venv
 
         c++ --version