Fix NetPacket path name typo.

[siadatism]

Running "pcap2mermaid.pl" causes this error (tested in Ubuntu 22.04 server):

Can't locate NetPacket/LinuxSLL.pm in @INC (you may need to install the NetPacket::LinuxSLL module) (@INC contains: ./lib/ /etc/perl /usr/local/lib/x86_64-linux-gnu/perl/5.34.0 /usr/local/share/perl/5.34.0 /usr/lib/x86_64-linux-gnu/perl5/5.34 /usr/share/perl5 /usr/lib/x86_64-linux-gnu/perl-base /usr/lib/x86_64-linux-gnu/perl/5.34 /usr/share/perl/5.34 /usr/local/lib/site_perl) at ./pcap2mermaid.pl line 7. BEGIN failed--compilation aborted at ./pcap2mermaid.pl line 7.

The problem is in "lib/Netpacket" name, that's a typo and should be changed to "lib/NetPacket" (capital P).