fix(alert): use correct variable

Author: thetaPC

core/src/components/alert/alert.ios.vars.scss

@@ -114,7 +114,7 @@ $alert-ios-input-padding-start: $alert-ios-input-padding-end;
 $alert-ios-input-placeholder-color: $placeholder-text-color;
 
 /// @prop - Border color of the alert input
-$alert-ios-input-border-color: var(--ion-color-text-250);
+$alert-ios-input-border-color: var(--ion-color-gray-250);
 
 /// @prop - Border of the alert input
 $alert-ios-input-border: $hairlines-width solid $alert-ios-input-border-color;