FunctionUtil: Accept bitdepths above max accepted bitdepth

Fix the removal of range.stop causing the highest bitdepth to be messed up.

Closes #155

vstools/functions/funcs.py

@@ -88,7 +88,7 @@ def __init__(
                 InvalidColorFamilyError.check(clip, color_family, func)
 
         if isinstance(bitdepth, tuple):
-            bitdepth = range(*bitdepth)
+            bitdepth = range(bitdepth[0], bitdepth[1] + 1)
 
         self.clip = clip
         self.planes = planes
@@ -114,7 +114,10 @@ def norm_clip(self) -> ConstantFormatVideoNode:
         from .. import get_depth
 
         if isinstance(self.bitdepth, (range, set)) and self.clip.format.bits_per_sample not in self.bitdepth:
-            clip = depth(self.clip, min(bits for bits in self.bitdepth if bits >= get_depth(self.clip)))
+            src_depth = get_depth(self.clip)
+            target_depth = next((bits for bits in self.bitdepth if bits >= src_depth), max(self.bitdepth))
+
+            clip = depth(self.clip, target_depth)
         elif isinstance(self.bitdepth, int):
             clip = depth(self.clip, self.bitdepth)
         else: