dbm.error: db type is dbm.gnu, but the module is not available

[amotl]

Describe the bug
After installing wetterdienst within a fresh micromamba environment and trying to acquire radar data using one of its example programs, it croaks.

To reproduce

1. Follow the installation at Run radar tests including wradlib on GHA #241 (comment).
2. Run example radar_sweep_hdf5.py.

   (base) wget https://raw.githubusercontent.com/earthobservations/wetterdienst/master/example/radar/radar_sweep_hdf5.py
   (base) python radar_sweep_hdf5.py
   

Expected behavior
Installing and invoking wetterdienst should just work (TM).

Version information
OS: macOS
Environment: micromamba

$ wetterdienst --version
wetterdienst 0.10.1

$ python -V
Python 3.8.6

$ micromamba --version
0.7.3

Additional context
Maybe it's related to the dogpile cache again? See also #217, #232 and #233.

Full traceback

Traceback (most recent call last):
  File "radar_sweep_hdf5.py", line 99, in <module>
    main()
  File "radar_sweep_hdf5.py", line 95, in main
    radar_hdf5_example()
  File "radar_sweep_hdf5.py", line 74, in radar_hdf5_example
    for item in request.collect_data():
  File "/Users/amo/dev/earthobservations/tmp/mamba/lib/python3.8/site-packages/wetterdienst/dwd/radar/access.py", line 169, in collect_radar_data
    file_index = create_fileindex_radar(
  File "<decorator-gen-5>", line 2, in create_fileindex_radar
  File "/Users/amo/dev/earthobservations/tmp/mamba/lib/python3.8/site-packages/dogpile/cache/region.py", line 1271, in get_or_create_for_user_func
    return self.get_or_create(key, user_func, timeout,
  File "/Users/amo/dev/earthobservations/tmp/mamba/lib/python3.8/site-packages/dogpile/cache/region.py", line 874, in get_or_create
    with Lock(
  File "/Users/amo/dev/earthobservations/tmp/mamba/lib/python3.8/site-packages/dogpile/lock.py", line 186, in __enter__
    return self._enter()
  File "/Users/amo/dev/earthobservations/tmp/mamba/lib/python3.8/site-packages/dogpile/lock.py", line 86, in _enter
    value = value_fn()
  File "/Users/amo/dev/earthobservations/tmp/mamba/lib/python3.8/site-packages/dogpile/cache/region.py", line 826, in get_value
    value = self.backend.get(key)
  File "/Users/amo/dev/earthobservations/tmp/mamba/lib/python3.8/site-packages/dogpile/cache/backends/file.py", line 220, in get
    with self._dbm_file(False) as dbm:
  File "/Users/amo/dev/earthobservations/tmp/mamba/lib/python3.8/contextlib.py", line 113, in __enter__
    return next(self.gen)
  File "/Users/amo/dev/earthobservations/tmp/mamba/lib/python3.8/site-packages/dogpile/cache/backends/file.py", line 213, in _dbm_file
    dbm = self.dbmmodule.open(
  File "/Users/amo/dev/earthobservations/tmp/mamba/lib/python3.8/dbm/__init__.py", line 91, in open
    raise error[0]("db type is {0}, but the module is not "
dbm.error: db type is dbm.gnu, but the module is not available

[amotl]

Again, this issue could be resolved by purging the cache directory, like rm -r ~/Library/Caches/wetterdienst.