Bump version on master

This commit does not represent a release and only synchronizes CHANGELOG
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src/changelog/v0.30.md

@@ -1,3 +1,24 @@
+## 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.
+
 ## 0.30.2
 
 ### Fixed