1.0.1: Fix keywords list in platform.io manifest

Fixes #1

Stand-alone release

After years as a copy&paste submodule in the libraries EspSoftwareSerial and CoopTask, ghostl has now been upgraded to full library status.
The major feature that gave the momentum for this move is the additional of full, portable support for C++ 20 coroutines targeted at all platforms from MCU to server.