Revert "Drop iOS 14 and macOS 11 support"

This reverts commit dcef7f47ff.

Shared/Views/OpenSettingsButton.swift

@@ -8,7 +8,7 @@ struct OpenSettingsButton: View {
     #endif
 
     var body: some View {
-        Button {
+        let button = Button {
             presentationMode.wrappedValue.dismiss()
 
             #if os(macOS)
@@ -20,7 +20,13 @@ struct OpenSettingsButton: View {
             Label("Open Settings", systemImage: "gearshape.2")
         }
         .buttonStyle(.plain)
-        .buttonStyle(.borderedProminent)
+
+        if #available(iOS 15.0, macOS 12.0, tvOS 15.0, *) {
+            button
+                .buttonStyle(.borderedProminent)
+        } else {
+            button
+        }
     }
 }