docs generation seems to be broken

[mikewilli]

The last few PR merges into main have resulted in the CI build-docs task failing:

  + Exception Group Traceback (most recent call last):
  |   File "/root/project/.script/generate_docs.py", line 22, in <module>
  |     "jetstream-config": ConfigCollection.from_github_repo(
  |   File "/root/project/venv/lib/python3.10/site-packages/metric_config_parser/config.py", line 354, in from_github_repo
  |     return ConfigCollection.from_local_repo(
  |   File "/root/project/venv/lib/python3.10/site-packages/metric_config_parser/config.py", line 438, in from_local_repo
  |     spec = AnalysisSpec.from_dict(default_config_json)
  |   File "/root/project/venv/lib/python3.10/site-packages/metric_config_parser/analysis.py", line 48, in from_dict
  |     return converter.structure(d, cls)
  |   File "/root/project/venv/lib/python3.10/site-packages/cattrs/converters.py", line 332, in structure
  |     return self._structure_func.dispatch(cl)(obj, cl)
  |   File "<cattrs generated structure metric_config_parser.analysis.AnalysisSpec>", line 40, in structure_AnalysisSpec
  |     if errors: raise __c_cve('While structuring ' + 'AnalysisSpec', errors, __cl)
  | cattrs.errors.ClassValidationError: While structuring AnalysisSpec (1 sub-exception)
  +-+---------------- 1 ----------------
    | Traceback (most recent call last):
    |   File "<cattrs generated structure metric_config_parser.analysis.AnalysisSpec>", line 6, in structure_AnalysisSpec
    |     res['metrics'] = __c_structure_metrics(o['metrics'], __c_type_metrics)
    |   File "/root/project/venv/lib/python3.10/site-packages/metric_config_parser/metric.py", line 380, in <lambda>
    |     converter.register_structure_hook(MetricsSpec, lambda obj, _type: MetricsSpec.from_dict(obj))
    |   File "/root/project/venv/lib/python3.10/site-packages/metric_config_parser/metric.py", line 322, in from_dict
    |     params["definitions"] = {
    |   File "/root/project/venv/lib/python3.10/site-packages/metric_config_parser/metric.py", line 324, in <dictcomp>
    |     {"name": k, **dict((kk.lower(), vv) for kk, vv in v.items())}, MetricDefinition
    | AttributeError: 'list' object has no attribute 'items'
    | Structuring class AnalysisSpec @ attribute metrics
    +------------------------------------