force setting a backgroundcolor im massageInputBar. Fixes white flashing in dark mode during animations

deltachat-ios/Chat/ChatViewController.swift

@@ -758,6 +758,7 @@ class ChatViewController: UITableViewController {
         messageInputBar.inputTextView.tintColor = DcColors.primary
         messageInputBar.inputTextView.textColor = DcColors.defaultTextColor
         messageInputBar.backgroundView.backgroundColor = DcColors.chatBackgroundColor
+        messageInputBar.backgroundColor = DcColors.chatBackgroundColor
         messageInputBar.inputTextView.backgroundColor = DcColors.inputFieldColor
         messageInputBar.inputTextView.placeholderTextColor = DcColors.placeholderColor
         messageInputBar.inputTextView.textContainerInset = UIEdgeInsets(top: 8, left: 16, bottom: 8, right: 38)