/// Encrypts a message using the Caesar cipher.
///
/// # Arguments
///
/// * `msg` - The plaintext message to encrypt
/// * `shift` - Number of positions to shift each byte
///
/// # Examples
///
/// ```
/// use cryptograph::cryptography::caesar::encrypt::caesar_encrypt;
///
/// let result = caesar_encrypt("hello", 3).unwrap();
/// assert_eq!(result, "khoor");
/// ```
///
/// # Errors
///
/// Returns `Err` if the resulting bytes are not valid UTF-8.