add changelog (#385)

Author: tlambert03

CHANGELOG.md

@@ -1,5 +1,27 @@
 # Changelog
 
+## [v0.4.0rc1](https://github.com/napari/magicgui/tree/v0.4.0rc1) (2022-03-18)
+
+[Full Changelog](https://github.com/napari/magicgui/compare/v0.3.7...v0.4.0rc1)
+
+**Implemented enhancements:**
+
+- Support sequences [\#342](https://github.com/napari/magicgui/pull/342) ([hanjinliu](https://github.com/hanjinliu))
+
+**Fixed bugs:**
+
+- Use empty string as null value for FileEdit [\#384](https://github.com/napari/magicgui/pull/384) ([brisvag](https://github.com/brisvag))
+- fix register\_widget with widget subclass [\#376](https://github.com/napari/magicgui/pull/376) ([tlambert03](https://github.com/tlambert03))
+
+**Deprecated:**
+
+- Remove event deprecations strategy \(for release 0.4.0\) [\#368](https://github.com/napari/magicgui/pull/368) ([tlambert03](https://github.com/tlambert03))
+
+**Tests & CI:**
+
+- Check out napari repo instead of git+https [\#378](https://github.com/napari/magicgui/pull/378) ([jni](https://github.com/jni))
+- Test that bound values don't get called greedily upon widget creation [\#371](https://github.com/napari/magicgui/pull/371) ([tlambert03](https://github.com/tlambert03))
+
 ## [v0.3.7](https://github.com/napari/magicgui/tree/v0.3.7) (2022-02-12)
 
 [Full Changelog](https://github.com/napari/magicgui/compare/v0.3.6...v0.3.7)