[Bug report] Cannot import after release 0.18.2 if shapely is not installed

### Describe the bug Cannot import after latest release Package uses `shapely.Geometry` as return type but shapely is an optional package and only imported in try..except. Issue introduced here: https://github.com/geoalchemy/geoalchemy2/commit/b6440a2fe70dd0629d3b882c8fb0e7bfba13f922#diff-deacd1a957b6264b25a2f4a5b2b1d9ccb3be0cb056e7e3d767363a17e66dbc06R38-R39 ### Optional link from https://geoalchemy-2.readthedocs.io which documents the behavior that is expected _No response_ ### To Reproduce ```Python uv pip install geoalchemy2 import geoalchemy2 ``` ### Error ```Python traceback (geol2) ➜ geol2 python Python 3.12.7 (main, Oct 16 2024, 07:12:08) [Clang 18.1.8 ] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> import geoalchemy2 Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/private/tmp/geol2/.venv/lib/python3.12/site-packages/geoalchemy2/__init__.py", line 3, in <module> from geoalchemy2 import admin File "/private/tmp/geol2/.venv/lib/python3.12/site-packages/geoalchemy2/admin/__init__.py", line 9, in <module> from geoalchemy2.admin import dialects File "/private/tmp/geol2/.venv/lib/python3.12/site-packages/geoalchemy2/admin/dialects/__init__.py", line 3, in <module> from geoalchemy2.admin.dialects import common # noqa ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/private/tmp/geol2/.venv/lib/python3.12/site-packages/geoalchemy2/admin/dialects/common.py", line 11, in <module> from geoalchemy2.types import Geometry File "/private/tmp/geol2/.venv/lib/python3.12/site-packages/geoalchemy2/types/__init__.py", line 33, in <module> from geoalchemy2.types import dialects File "/private/tmp/geol2/.venv/lib/python3.12/site-packages/geoalchemy2/types/dialects/__init__.py", line 4, in <module> from geoalchemy2.types.dialects import geopackage # noqa ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/private/tmp/geol2/.venv/lib/python3.12/site-packages/geoalchemy2/types/dialects/geopackage.py", line 3, in <module> from geoalchemy2.types.dialects.sqlite import bind_processor_process # noqa ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/private/tmp/geol2/.venv/lib/python3.12/site-packages/geoalchemy2/types/dialects/sqlite.py", line 9, in <module> from geoalchemy2.shape import to_shape File "/private/tmp/geol2/.venv/lib/python3.12/site-packages/geoalchemy2/shape.py", line 38, in <module> def to_shape(element: WKBElement | WKTElement) -> shapely.Geometry: ^^^^^^^ NameError: name 'shapely' is not defined ``` ### Additional context _No response_ ### GeoAlchemy 2 Version in Use 0.18.2 ### Python Version 3.12 ### Operating system MacOS