Remove get_pypam_version

Client code can use something like:

        import importlib.metadata

        return importlib.metadata.version("lifewatch-pypam")

pypam/__init__.py

@@ -1,17 +1,5 @@
-"""
-Main PyPAM module.
-"""
-__version__ = "0.3.0"
-
 from pypam.dataset import DataSet
 from pypam.acoustic_survey import ASA
 from pypam.acoustic_file import AcuFile
 from pypam.signal import Signal
 from pypam.detection import Detection
-
-
-def get_pypam_version():
-    """
-    Get the version of the pypam package.
-    """
-    return __version__