adding apt install step (#4795)

Author: aishwaryabh

eng/ci/templates/official/jobs/linux-deb-build-pack.yml

@@ -30,6 +30,7 @@ jobs:
       sudo apt-get update
       sudo apt-get install -y binutils-aarch64-linux-gnu
       sudo apt-get install -y fakeroot
+      sudo apt-get install -y python3-venv
     displayName: 'Install required tools'
 
   - task: PowerShell@2