Roadmapper

- Removed the dependency of Arial font on Linux system. i.e. The following commands to install MSCoreFonts is no longer required.
- sudo apt install ttf-mscorefonts-installer
- sudo fc-cache -f
- Code clean up

- Fixed [20](https://github.com/csgoh/roadmapper/issues/20): Removed absolute font naming dependency. i.e. "arial.ttf"
- Fixed [22](https://github.com/csgoh/roadmapper/issues/22): The date argument for add_timeline() method is now passed as keyword argument. e.g. add_timeline(start="2023-05-16")
- Introduced the 'with' statement for context management to create cleaner code.

First major release