Revert "pkg: do not yet verify the fingerprints"

This reverts commit 4df19f1b.
It's time to enable the verification.  the packagaes are being
signed since the original commit went in and all tests have
shown that this works as expected.  Staying safe, you know...

pkg/OPNsense.conf

 OPNsense: {
+  fingerprints: "/usr/local/etc/pkg/fingerprints/OPNsense",
   url: "pkg+http://pkg.opnsense.org/${ABI}/latest",
+  signature_type: "fingerprints",
   mirror_type: "srv",
   priority: 11,
   enabled: yes