pure-ftpd-wrapper does not parse all config files

[Thorsten Kunz]

Binary package hint: pure-ftpd-common

The script failed to read these two configuration files: IPV4Only, IPV6Only

This is due to a regular expression that only permits config files with characters but no digits.

Fix: change line 154 in pure-ftpd-wrapper from

next unless /^[A-Za-z]+$/;

to

next unless /^[A-Za-z0-9]+$/;

to allow digits in config file names.