netinet tests: Move import

[jlduran]

Summary

This will allow the test to be skipped if scapy is not installed.

[kp]

I think I'd like a slightly more verbose commit message for this.

Perhaps:

Move the import of 'Sniffer', which depends on scapy into the test so we don't try (and fail) to import it unless scapy is installed.

[jlduran]

In D48945#1116557, @kp wrote:

I think I'd like a slightly more verbose commit message for this.

Perhaps:

Move the import of 'Sniffer', which depends on scapy into the test so we don't try (and fail) to import it unless scapy is installed.

Excellent, thank you. Will update upon commit.