Bump lib version (backport #873) (#887)

* Bump lib version (#873)

(cherry picked from commit df623c0)

# Conflicts:
#	library.properties

* Update library.properties

Co-authored-by: Antonio Cuadros <[email protected]>

Author: mergify[bot]

library.properties

@@ -1,5 +1,5 @@
 name=micro_ros_arduino
-version=2.0.3-rolling
+version=2.0.4-rolling
 author=micro-ROS
 maintainer=Pablo Garrido <[email protected]>
 sentence=micro-ROS Arduino library