set deviceupdate release date (Azure#29754)

* set deviceupdate release date

* remove empty block in CHANGELOG.md

Author: chunyu3

sdk/deviceupdate/Azure.IoT.DeviceUpdate/CHANGELOG.md

@@ -1,6 +1,6 @@
 # Release History
 
-## 1.0.0-beta.4 (Unreleased)
+## 1.0.0-beta.4 (2022-07-11)
 
 ### Features Added
 - Added RelatedFiles and DownloadHandler to Update
@@ -16,10 +16,6 @@
 - DeviceUpdateClient models updated
 - DeviceManagementClient models updated
 
-### Bugs Fixed
-
-### Other Changes
-
 ## 1.0.0-beta.3 (2022-01-17)
 
 ### Features Added