Fix the inverted logic from the previous lark change. (#626)
Fix the inverted logic from the previous lark change. (#626)

It was just completely backwards, so didn't end up installing
the package from pip when needed.

Signed-off-by: Chris Lalancette <281cd07d7578d97c83271fbbf2faddb83ab3791c@openrobotics.org>
ros2/ci,ros2/ci,ros2/ci