Bug Fix: Plugins Fail To Load on Python 3.8+ (#505)

* Set fork multiprocessing as the upgrade to python 3.8 switched to spawn processing which does not share memory between child processes.

* Pass settings object into child processes. Create the baseline json only once

Co-authored-by: John-Paul Dakran <dakranj@c02g1288md6q.phub.net.cable.rogers.com>

detect_secrets/core/secrets_collection.py

@@ -11,6 +11,8 @@
 
 from . import scan
 from .potential_secret import PotentialSecret
+from detect_secrets.settings import configure_settings_from_baseline
+from detect_secrets.settings import get_settings
 
 
 class PatchedFile:
@@ -55,7 +57,13 @@ def scan_files(self, *filenames: str, num_processors: Optional[int] = None) -> N
         if not num_processors:
             num_processors = mp.cpu_count()
 
-        with mp.Pool(processes=num_processors) as p:
+        child_process_settings = get_settings().json()
+
+        with mp.Pool(
+            processes=num_processors,
+            initializer=configure_settings_from_baseline,
+            initargs=(child_process_settings,),
+        ) as p:
             for secrets in p.imap_unordered(
                 _scan_file_and_serialize,
                 [os.path.join(self.root, filename) for filename in filenames],