Remove unnecessary assignment

Removed unnecessary type annotation for _obj.

Author: florian-huber

spec2vec/SpectrumDocument.py

@@ -54,7 +54,6 @@ def __init__(self, spectrum: Spectrum, n_decimals: int = 2):
         self.weights = None
         super().__init__(obj=spectrum)
         self._add_weights()
-        self._obj: Spectrum = self._obj
 
     def _make_words(self) -> list[str]:
         """Create word from peaks (and losses)."""