tools: Fix style issues in virt-qemu-sev-validate

The script had an incorrect interpreter line until commit
f6a19d7264, so the flake8 check would not realize it needed
to pick it up and these issues, some of which were present it
the very first version that was committed, were not being
reported.

Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>

tools/virt-qemu-sev-validate

@@ -1331,5 +1331,6 @@ def main():
             print("ERROR: %s" % e, file=sys.stderr)
         sys.exit(6)
 
+
 if __name__ == "__main__":
     main()