Bump version to 0.3.0 (#54)
List of changes since v0.2.0:
* Renderer argument for Collagraph is now required (#43)
* Fix an issue with garbage collection icw Qt event loop (#49)
* Render output is now watched instead of props and state to trigger updates (#52)
* Component changes:
* Add support for events in components (#40)
* Add support for slots (#42)
* CGX improvements and changes:
* Improve debugging of python script content of CGX files (#38)
* Add support for component classes and functions (#36)
* Template tags that start with a capital or contain a dot are assumed to be component class or function (#36)
* Add support for slot in template (#44)
* Fix for simple expressions in v-if and v-for directives (#53)
* Fix for multiple v-if statements directly following each other (#53)
* PySide renderer improvements
* Add support for resizing widgets (#36)
* Add support for QEvents (#36)
* Allow for widgets as top-level elements (windows) (#36)
* Add support for changing of widget layouts (#36)
* Allow for re-rendering top-level widgets (#48)
* Menus and actions are now
* Pygfx renderer improvements
* Cache pygfx package lookups (#36)
