Contact Form 7 change text of select include_blank

wpcf7_form_elements
/**
 * Customize the default option selected on CF7
 */</span>
 <span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">my_wpcf7_form_elements</span>(<span class="hljs-params">$html</span>) </span>{
    $text = <span class="hljs-string">'—'</span>;
    $html = str_replace(<span class="hljs-string">'---'</span>,  $text , $html);
    <span class="hljs-keyword">return</span> $html;
}
add_filter(<span class="hljs-string">'wpcf7_form_elements'</span>, <span class="hljs-string">'my_wpcf7_form_elements'</span>);

Source: