processingLevel mapping issue during dedl product types discovery

[sbrunato]

There is an issue with processingLevel mapping issue during dedl product types discovery:

dag.list_product_types("dedl")

   File "/home/sylvain/workspace/eodag/eodag/api/core.py", line 595, in list_product_types
    self.fetch_product_types_list(provider=provider)
  File "/home/sylvain/workspace/eodag/eodag/api/core.py", line 772, in fetch_product_types_list
    self.update_product_types_list(provider_ext_product_types_conf)
  File "/home/sylvain/workspace/eodag/eodag/api/core.py", line 937, in update_product_types_list
    self.build_index()
  File "/home/sylvain/workspace/eodag/eodag/api/core.py", line 320, in build_index
    ix_writer.add_document(
  File "/home/sylvain/.virtualenvs/eodag-dev/lib/python3.12/site-packages/whoosh/writing.py", line 750, in add_document
    for tbytes, freq, weight, vbytes in items:
  File "/home/sylvain/.virtualenvs/eodag-dev/lib/python3.12/site-packages/whoosh/fields.py", line 164, in index
    for tstring, freq, wt, vbytes in word_values(value, ana, **kwargs):
                                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/sylvain/.virtualenvs/eodag-dev/lib/python3.12/site-packages/whoosh/formats.py", line 146, in word_values
    wordset = set(t.text for t in tokens(value, analyzer, kwargs))
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: unhashable type: 'list'

The processingLevel is returned as a lsit of list and should not:

{'ID': 'EO.EUM.DAT.MULT.HIRSL1', 'processingLevel': [['L1']], ...}