Fix image named circle.fill for iOS 12

Pre iOS 13, Xcode will assume ".fill" is a bad path extension and use "circle" as image

Signed-off-by: Henrik Storch <henrik.storch@nextcloud.com>

iOSClient/Share/NCShareCommon.swift

@@ -45,7 +45,7 @@ class NCShareCommon: NSObject {
 
         let size: CGFloat = 200
 
-        let bottomImage = UIImage(named: "circle.fill")!.image(color: colorCircle, size: size/2)
+        let bottomImage = UIImage(named: "circle_fill")!.image(color: colorCircle, size: size/2)
         let topImage = UIImage(named: imageName)!.image(color: .white, size: size/2)
         UIGraphicsBeginImageContextWithOptions(CGSize(width: size, height: size), false, UIScreen.main.scale)
         bottomImage.draw(in: CGRect(origin: CGPoint.zero, size: CGSize(width: size, height: size)))