Update p0f to version 3.0.7b, add test

- Update p0f to version 3.0.7b.
- Add a simple test in which p0f reads a pcap file.

In the test we write a simple binary pcap file (included in the recipe base64-encoded) and then attempt to read the file with p0f.

Oh, you already did! https://github.com/Homebrew/homebrew/pull/32869