Fix error when reading Velox file containing FFT with odd number of pixels

[ericpre]

Port hyperspy/hyperspy#3040 to RosettaSciIO with test files as provided by @bryandesser.

Progress of the PR

• Add missing dtype to list of expected dtype for complex signal,
• [n/a] update docstring (if appropriate),
• [n/a] update user guide (if appropriate),
• add an changelog entry in the upcoming_changes folder (see upcoming_changes/README.rst),
• Check formatting changelog entry in the readthedocs doc build of this PR (link in github checks)
• add tests,
• ready for review.

[codecov]

Codecov Report

Base: 83.37% // Head: 83.37% // No change to project coverage 👍

Coverage data is based on head (6689b57) compared to base (8176d44).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #49   +/-   ##
=======================================
  Coverage   83.37%   83.37%           
=======================================
  Files          40       40           
  Lines        8337     8337           
  Branches     1896     1896           
=======================================
  Hits         6951     6951           
  Misses        911      911           
  Partials      475      475           

Impacted Files	Coverage Δ
rsciio/emd/api.py	85.34% <100.00%> (ø)

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