Random number generator uses wrong API

The code tries to access `time.clock()` which doesn't exist (in my Python distribution).
On Unix there is `time.clock_gettime(key)` and `time.clock_gettime_ns(key)` or `time.perf_counter()` and `time.perf_counter_ns()`.

I tested with Miniforge3 (CPython) and Miniconda3, simply installed via `conda install pycrypto`.

```
        p = KeyPair()
      File "d:\forks\hace\autocook\autocook\encryption.py", line 33, in __init__
        _.key = key = RSA.generate(KEY_SIZE_BITS, Random.new().read) # using minimum allowed key length
      File "c:\programdata\Miniconda3\envs\py38\lib\site-packages\Crypto\PublicKey\RSA.py", line 508, in generate
        obj = _RSA.generate_py(bits, rf, progress_func, e) # TODO: Don't use legacy _RSA module
      File "c:\programdata\Miniconda3\envs\py38\lib\site-packages\Crypto\PublicKey\_RSA.py", line 50, in generate_py
        p = pubkey.getStrongPrime(bits>>1, obj.e, 1e-12, randfunc)
      File "c:\programdata\Miniconda3\envs\py38\lib\site-packages\Crypto\Util\number.py", line 282, in getStrongPrime
        X = getRandomRange (lower_bound, upper_bound, randfunc)
      File "c:\programdata\Miniconda3\envs\py38\lib\site-packages\Crypto\Util\number.py", line 123, in getRandomRange
        value = getRandomInteger(bits, randfunc)
      File "c:\programdata\Miniconda3\envs\py38\lib\site-packages\Crypto\Util\number.py", line 104, in getRandomInteger
        S = randfunc(N>>3)
      File "c:\programdata\Miniconda3\envs\py38\lib\site-packages\Crypto\Random\_UserFriendlyRNG.py", line 202, in read
        return self._singleton.read(bytes)
      File "c:\programdata\Miniconda3\envs\py38\lib\site-packages\Crypto\Random\_UserFriendlyRNG.py", line 178, in read
        return _UserFriendlyRNG.read(self, bytes)
      File "c:\programdata\Miniconda3\envs\py38\lib\site-packages\Crypto\Random\_UserFriendlyRNG.py", line 129, in read
        self._ec.collect()
      File "c:\programdata\Miniconda3\envs\py38\lib\site-packages\Crypto\Random\_UserFriendlyRNG.py", line 77, in collect
        t = time.clock()
    AttributeError: module 'time' has no attribute 'clock'
**********************************************************************
```