Fix VRT rules tarball filename so 2.9.4.1 rules download instead of 2.9.4.0

CHANGE LOG
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Correct typo for Snort VRT rules tarball filename so it correctly references the tarball 
for Snort version 2.9.4.1.  The Shared Object pre-compiled rules changed slightly 
in 2.9.4.1 and the pre-compiled objects in the 2.9.4.0 tarball will not work with Snort 
2.9.4.1.