Duplicated metadata keys are not handled correctly

[misialq]

When fetching metadata containing some duplicated keys, the processing fails.

Steps to reproduce:

• fetch metadata for sample SRR5498984 with qiime fondue get-metadata ...

Expected behaviour:

• metadata gets fetched without an issue
• the non-required metadata fields should rather all be included with a suffix in case of duplicates

Actual behaviour:

• fetching fails with the following error ("BioSampleModel" is duplicated):

  Traceback (most recent call last):
  File "/Users/mziemski/miniconda3/envs/fondue/lib/python3.8/threading.py", line 932, in _bootstrap_inner
  self.run()
  File "/Users/mziemski/miniconda3/envs/fondue/lib/python3.8/site-packages/entrezpy/requester/threadedrequest.py", line 48, in run
  self.run_one_request(request, analyzer)
  File "/Users/mziemski/miniconda3/envs/fondue/lib/python3.8/site-packages/entrezpy/requester/threadedrequest.py", line 71, in run_one_request
  analyzer.parse(response, request)
  File "/Users/mziemski/miniconda3/envs/fondue/lib/python3.8/site-packages/q2_fondue/entrezpy_clients/_efetch.py", line 295, in parse
  self.analyze_result(response, request)
  File "/Users/mziemski/miniconda3/envs/fondue/lib/python3.8/site-packages/q2_fondue/entrezpy_clients/_efetch.py", line 289, in analyze_result
  self.result.add_metadata(response, request.uids)
  File "/Users/mziemski/miniconda3/envs/fondue/lib/python3.8/site-packages/q2_fondue/entrezpy_clients/_efetch.py", line 265, in add_metadata
  self.metadata[uid] = self._process_single_run(
  File "/Users/mziemski/miniconda3/envs/fondue/lib/python3.8/site-packages/q2_fondue/entrezpy_clients/_efetch.py", line 71, in _process_single_run
  processed_meta = self._extract_custom_attributes(
  File "/Users/mziemski/miniconda3/envs/fondue/lib/python3.8/site-packages/q2_fondue/entrezpy_clients/_efetch.py", line 107, in _extract_custom_attributes
  raise DuplicateKeyError(
  q2_fondue.entrezpy_clients._efetch.DuplicateKeyError: One of the metadata keys (BioSampleModel) is duplicated.

[misialq]

Closed by #22