software/slapos-testing: add jq, sed and grep in PATH

This is used by caucase.sh test
4 jobs for feat/testing-caucase-sh-deps in 0 seconds
Status Job ID Name Coverage
  External
passed SlapOS.Eggs.UnitTest-Jerome.Python2

00:11:12

passed SlapOS.Eggs.UnitTest-Jerome.Python3

00:22:47

running SlapOS.SlapRunner.ResilienceTest-Master

26705:05:00

running SlapOS.SoftwareReleases.IntegrationTest-Master.Python2

26705:05:07