Winit version 0.30.3

Added

• On Web, add EventLoopExtWebSys::(set_)poll_strategy() to allow setting
  control flow strategies before starting the event loop.
• On Web, add WaitUntilStrategy, which allows to set different strategies for
  ControlFlow::WaitUntil. By default the Prioritized Task Scheduling API is
  used, with a fallback to setTimeout() with a trick to circumvent throttling
  to 4ms. But an option to use a Web worker to schedule the timer is available
  as well, which commonly prevents any throttling when the window is not focused.

Changed

• On macOS, set the window theme on the NSWindow instead of application-wide.

Fixed

• On X11, build on arm platforms.
• On macOS, fixed WindowBuilder::with_theme not having any effect on the window.