Remove invalid regex

[miken32]

Resolves #1927

Before submitting your PR, please review the following checklist:

• CHOOSE CORRECT BRANCH: if filing a bugfix/enhancement
  against 0.9.x series, choose master branch
• CONSIDER adding a unit test if your PR resolves an issue
• LIST ISSUES this PR resolves
• MAKE SURE this PR doesn't break existing tests
• KEEP PR small so it could be easily reviewed.
• AVOID making unnecessary stylistic changes in unrelated code
• ACCOMPANY each new failregex for filter X with sample log lines
  within fail2ban/tests/files/logs/X file

[coveralls]

Coverage remained the same at 91.956% when pulling 3f715e8 on miken32:patch-1 into c42dd69 on fail2ban:master.

[coveralls]

Coverage remained the same at 91.956% when pulling 3f715e8 on miken32:patch-1 into c42dd69 on fail2ban:master.

[codecov-io]

Codecov Report

Merging #1929 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1929   +/-   ##
=======================================
  Coverage   89.71%   89.71%           
=======================================
  Files          68       68           
  Lines        7431     7431           
  Branches     1020     1020           
=======================================
  Hits         6667     6667           
  Misses        598      598           
  Partials      166      166

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[sebres]

Please add a change log entry, then I'll merge it.

[miken32]

Change log updated. Can this get merged onto other branches as well? Same regex is in all versions.