title: FutureWarning: The default value of regex will change from True to False in a future version
body: <p>I'm running below code to clean text</p>
  <pre><code>import pandas as pd
  
  def not_regex(pattern):
          return r&quot;((?!{}).)&quot;.format(pattern)
      
  tmp = pd.DataFrame(['No one has a European accent either @',
                      'That the kid   reminds me of Kevin'])
  
  tmp[0].str.replace(not_regex('(\\b[-/]\\b|[a-zA-Z0-9])'), ' ') 
  </code></pre>
  <p>Then it returns a warning</p>
  <pre><code>&lt;ipython-input-8-ef8a43f91dbd&gt;:9: FutureWarning: The default value of regex will change from True to False in a future version.
    tmp[0].str.replace(not_regex('(\\b[-/]\\b|[a-zA-Z0-9])'), ' ')
  </code></pre>
  <p>Could you please elaborate on the reason of this warning?</p>