chore: run dartfmt on changed files

packages/stream_chat_flutter/lib/src/channel_preview.dart

@@ -249,7 +249,8 @@ class ChannelPreview extends StatelessWidget {
                 lastMessage.mentionedUsers,
                 lastMessage.attachments,
                 chatThemeData.channelPreviewTheme.subtitleStyle?.copyWith(
-                    color: chatThemeData.channelPreviewTheme.subtitleStyle?.color,
+                    color:
+                        chatThemeData.channelPreviewTheme.subtitleStyle?.color,
                     fontStyle: (lastMessage.isSystem || lastMessage.isDeleted)
                         ? FontStyle.italic
                         : FontStyle.normal),

packages/stream_chat_flutter/lib/src/theme/channel_preview_theme.dart

@@ -54,7 +54,8 @@ class ChannelPreviewTheme {
     if (other == null) return this;
     return copyWith(
       title: titleStyle?.merge(other.titleStyle) ?? other.titleStyle,
-      subtitle: subtitleStyle?.merge(other.subtitleStyle) ?? other.subtitleStyle,
+      subtitle:
+          subtitleStyle?.merge(other.subtitleStyle) ?? other.subtitleStyle,
       lastMessageAt:
           lastMessageAt?.merge(other.lastMessageAt) ?? other.lastMessageAt,
       avatarTheme: avatarTheme?.merge(other.avatarTheme) ?? other.avatarTheme,