[performance] SquashFS: Disable redundant and interfering buffering f…

…or SquashFS image reads

core/ratarmountcore/SquashFSMountSource.py

@@ -408,7 +408,7 @@ def __init__(
         **options
         # fmt: on
     ) -> None:
-        self.rawFileObject = open(fileOrPath, 'rb') if isinstance(fileOrPath, str) else fileOrPath
+        self.rawFileObject = open(fileOrPath, 'rb', 0) if isinstance(fileOrPath, str) else fileOrPath
         self.rawFileObject.seek(0)
         offset = findSquashFSOffset(self.rawFileObject)
         if offset < 0: