Using multiprocessing start method fork on Linux to avoid issues with Python 3.14. Fixes #35.

LXMF/LXStamper.py

@@ -15,6 +15,8 @@ PN_VALIDATION_POOL_MIN_SIZE     = 256
 
 active_jobs = {}
 
+if RNS.vendor.platformutils.is_linux(): multiprocessing.set_start_method("fork")
+
 def stamp_workblock(material, expand_rounds=WORKBLOCK_EXPAND_ROUNDS):
     wb_st = time.time()
     workblock = b""