fix value label's text color of BasicCell

deltachat-ios/View/BasicCell.swift

@@ -26,7 +26,7 @@ class BasicCell: UITableViewCell {
         let label = UILabel()
         label.font = .preferredFont(forTextStyle: .body)
         label.adjustsFontForContentSizeCategory = true
-        label.textColor = .darkGray
+        label.textColor = .systemGray
         label.lineBreakMode = .byTruncatingTail
         label.translatesAutoresizingMaskIntoConstraints = false
         label.setContentHuggingPriority(.defaultHigh, for: NSLayoutConstraint.Axis.horizontal)