switch to multiprocessing.dummy to avoid unnecessary separate processes

[ryran]

Turns out multiprocessing.dummy works just as well and uses threads instead of separate processes! Sweet! Guess I'll be changing the cmdline opt back to --threads.

[ryran]

Yay! Done.

$ rhsecapi --help | grep -A1 -- --threads
  -t, --threads THREDS  Set number of concurrent worker threads to allow when
                        making CVE queries (default on this system: 5)

[ryran]

Yay! Done.

$ rhsecapi --help | grep -A1 -- --threads
  -t, --threads THREDS  Set number of concurrent worker threads to allow when
                        making CVE queries (default on this system: 5)