fix(ios): use updated API to query biometrics + pin fallback for ios 9 and above

the existing "LAPolicyDeviceOwnerAuthenticationWithBiometrics" is no longer recommended, and does
not provide a pin/password fallback. The new "LAPolicyDeviceOwnerAuthentication" provides both as
expected. But since this is only available on ios 9 and above - a fallback to the old way is
included.

Author: LonelyCpp

ios/RNBiometrics.m

@@ -34,7 +34,12 @@ @implementation RNBiometrics
         LAContext *context = [[LAContext alloc] init];
         context.localizedFallbackTitle = title;
 
-        [context evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics localizedReason:promptMessage reply:^(BOOL success, NSError *biometricError) {
+        LAPolicy localAuthPolicy = LAPolicyDeviceOwnerAuthenticationWithBiometrics;
+        if (![[UIDevice currentDevice].systemVersion hasPrefix:@"8."]) {
+            localAuthPolicy = LAPolicyDeviceOwnerAuthentication;
+        }
+        
+        [context evaluatePolicy:localAuthPolicy localizedReason:promptMessage reply:^(BOOL success, NSError *biometricError) {
             if (success) {
                 resolve( @(YES));