fix: non-nullable error

[jonasbadstuebner]

I got the following error multiple times:

hosted/pub.dev/pointycastle-3.7.3/lib/key_derivators/argon2_native_int_impl.dart:645:7: Error: Field 'pass' should be initialized because its type 'int' doesn't allow null.
  int pass;
      ^^^^
hosted/pub.dev/pointycastle-3.7.3/lib/key_derivators/argon2_native_int_impl.dart:646:7: Error: Field 'lane' should be initialized because its type 'int' doesn't allow null.
  int lane;
      ^^^^
hosted/pub.dev/pointycastle-3.7.3/lib/key_derivators/argon2_native_int_impl.dart:647:7: Error: Field 'slice' should be initialized because its type 'int' doesn't allow null.
  int slice;
      ^^^^^

With overridden dependencies on the failing command it works from my fork now.