GHSA-6878-6wc2-pf5h

**Problem**: Trying to create a new encrypted message with the same cocoon object generates the same ciphertext. It mostly affects `MiniCocoon` and `Cocoon` objects with custom seeds and RNGs (where `StdRng` is used under the hood).

**Note**: The issue does **NOT** affect objects created with **`Cocoon::new`** which utilizes `ThreadRng`.

**Cause**: `StdRng` produces the same nonce because `StdRng::clone` resets its state.

**Measure**: Make encryption API mutable (`encrypt`, `wrap`, and `dump`).

**Workaround**: Create a new cocoon object with a new **seed** per each encryption.

## How to Reproduce

```rust let cocoon = MiniCocoon::from_password(b"password", &[1; 32]); let mut data1 = "my secret data".to_owned().into_bytes(); let _ = cocoon.encrypt(&mut data1)?;

let mut data2 = "my secret data".to_owned().into_bytes(); let _ = cocoon.encrypt(&mut data2)?;

// data1: [23, 217, 251, 151, 179, 62, 85, 15, 253, 92, 192, 112, 200, 52] // data2: [23, 217, 251, 151, 179, 62, 85, 15, 253, 92, 192, 112, 200, 52] ```

## Workaround

For `cocoon <= 0.3.3`, create a new cocoon with a different **seed** per each `encrypt`/`wrap`/`dump` call.

```rust let cocoon = MiniCocoon::from_password(b"password", &[1; 32]); let mut data1 = "my secret data".to_owned().into_bytes(); let _ = cocoon.encrypt(&mut data1)?;

// Another seed: &[2; 32]. let cocoon = MiniCocoon::from_password(b"password", &[2; 32]); let mut data2 = "my secret data".to_owned().into_bytes(); let _ = cocoon.encrypt(&mut data2)?;

// data1: [23, 217, 251, 151, 179, 62, 85, 15, 253, 92, 192, 112, 200, 52] // data2: [53, 223, 209, 96, 130, 99, 209, 108, 83, 189, 123, 81, 19, 1] ```