Fix missing parenthesis in EncodingVisualizer.calculate_label_colors

[Liam-DeVoe]

from tokenizers.tools import EncodingVisualizer, Annotation

annotations = [Annotation(start=0, end=1, label="annotation")]
# actual   hsl(10,32%,64%
# expected hsl(10,32%,64%)
EncodingVisualizer.calculate_label_colors(annotations)["annotation"]

fwiw: I found this bug during a research project I'm working on which uses LLMs to write property-based tests in Hypothesis. This property, that the hsl string should be valid, was proposed and written "autonomously" by the agent. I wrote this PR myself and take full responsibility for it.

[ArthurZucker]

Thanks 🤗