Fix for __version__ (#220)

Now
```python
>>> import uuid6
>>> uuid6.__version__
'0.0.0.dev0'
```

Author: shadchin

src/uuid6/__init__.py

@@ -4,18 +4,14 @@
 generating version 6, 7, and 8 UUIDs as specified in RFC 9562.
 """
 
-# Get version
-try:
-    from ._version import version as __version__  # type: ignore
-except ImportError:
-    __version__ = "0.0.0.dev0"
-
-
+import importlib.metadata
 import secrets
 import time
 import uuid
 from typing import Optional, Tuple
 
+__version__ = importlib.metadata.version(__package__)
+
 
 class UUID(uuid.UUID):
     r"""Instances of the UUID class represent UUIDs as specified in RFC 9562."""