Allow freezing the micro-ROS package versions

[bjsowa]

I got back to working on my project after a couple of months. When I tried to build it, it no longer compiled because the library builder pulled newer version of micro-ROS packages that contained API changes that were not compatible with my code.

I think this library should either be tied to specific versions of the packages and have a library auto-update workflow (similar to the on micro_ros_arduino) or allow the user to specify the versions.

[pablogs9]

Here is a good point to specify fixed commits or tags for each micro-ROS package. Please open a PR if you have any solution.

[patrickwasp]

@bjsowa you can try using the version in the URL in your lib_deps

lib_deps = 
	https://github.com/micro-ROS/micro_ros_platformio#1.0.0