title: How to use min value with type datetime in Cerberus?
body: <p>I want validate a field with one value greater or equal 01/01/1900 in type datetime in Cerberus, but not works this way:</p>
  <pre><code>from cerberus import Validator 
  from datetime import datetime
      
  v = Validator()
  schema = {
      &quot;birthdate&quot;: {
          &quot;type&quot;: &quot;datetime&quot;,
          &quot;required&quot;: True,
          &quot;min&quot;: datetime(1900, 1, 1)
      }
  }
  document_valid = {'birthdate': '05/03/1900'}
  document_invalid = {'birthdate': '05/03/1800'}
  
  print(v.validate(document_valid, schema)) # I want this True
  print(v.validate(document_invalid, schema)) # I want this False
  </code></pre>
  <p>Anyone could help me?</p>
  <p>I'm using this version to Cerberus: <code>Cerberus==1.3.4</code></p>