Pin empy version to 3.3.4 inside Dockerfile (#273)

* fix: Pin empy version to 3.3.4

* docs: Mention that empy has to be pinned to version 3.3.4

Author: 2b-t

README.md

@@ -11,7 +11,7 @@ This component needs `colcon` and other Python 3 packages inside the IDF virtual
 
 ```bash
 . $IDF_PATH/export.sh
-pip3 install catkin_pkg lark-parser colcon-common-extensions
+pip3 install catkin_pkg lark-parser colcon-common-extensions empy==3.3.4
 ```
 
 ## Middlewares available

docker/install_micro_ros_deps_script.sh

@@ -5,6 +5,6 @@ set -eu
 sudo apt update -q
 sudo apt install -yq python3-pip
 source $IDF_PATH/export.sh
-pip3 install catkin_pkg lark-parser colcon-common-extensions importlib-resources
+pip3 install catkin_pkg lark-parser colcon-common-extensions importlib-resources empy==3.3.4
 
 set +u