fix(hdf5): read HDF5_BACKEND_VERSION using actual stored type(#42)

[prasad-sawantdesai]

$ python
Python 3.11.5 (main, Jul 30 2025, 19:17:56) [GCC 13.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import imas
>>> with imas.DBEntry("imas:hdf5?path=./HSDS-imas/hsds", "r") as dbentry:
...     ids = dbentry.get("pf_active")
... 
13:01:49 INFO     Parsing data dictionary version 4.1.1 @dd_zip.py:89
13:01:50 INFO     Parsing data dictionary version 4.0.0 @dd_zip.py:89
>>> ids
<IDSToplevel (IDS:pf_active)>
         
>>> imas.util.print_tree(ids)
pf_active
├── ids_properties
│   ├── comment: 'testing pf_active'
│   ├── homogeneous_time: 1
│   └── ids_properties/version_put
│       ├── data_dictionary: '4.0.0'
│       ├── access_layer: '5.4.3'
│       └── access_layer_language: 'imas 2.0.0.post1'
└── time: array([0.01])
>>> with imas.DBEntry("imas:hdf5?path=./HSDS-imas/hsds", "r") as dbentry:
...     ids = dbentry.get("equilibrium")
... 
>>> ids
<IDSToplevel (IDS:equilibrium)>
>>> imas.util.print_tree(ids)
equilibrium
├── ids_properties
│   ├── comment: 'testing'
│   ├── homogeneous_time: 1
│   └── ids_properties/version_put
│       ├── data_dictionary: '4.0.0'
│       ├── access_layer: '5.4.3'
│       └── access_layer_language: 'imas 2.0.0.post1'
└── time: array([0.01])
>>> 
[3]+  Stopped                 python
[sawantp1@98dci4-srv-1003 IMAS-Core]$ 

[olivhoenen]

@fleuryl-ai are you happy with this update?