Increase tolerance in digitalsurf tests

[ericpre]

Some more tweaks of the tolerance in the digitalsurf tests to reduce the occurrence of occasional failure. This happens because of save/read cycle using compression and it is not fully reproducible and it will also on the environment and the binaries used.
Based on:
https://github.com/hyperspy/hyperspy-extensions-list/actions/runs/23523113755/job/68470456510
https://github.com/hyperspy/hyperspy-extensions-list/actions/runs/23523113755/job/68470456520
https://github.com/hyperspy/hyperspy-extensions-list/actions/runs/23523113755/job/68470456463

Progress of the PR

• Increase tolerance,
• [n/a] update docstring (if appropriate),
• [n/a] update user guide (if appropriate),
• [n/a] add a changelog entry in the upcoming_changes folder (see upcoming_changes/README.rst),
• [n/a] Check formatting of the changelog entry (and eventual user guide changes) in the docs/readthedocs.org:rosettasciio build of this PR (link in github checks)
• update tests,
• ready for review.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.31%. Comparing base (30ca9dd) to head (5558068).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #497   +/-   ##
=======================================
  Coverage   88.31%   88.31%           
=======================================
  Files         108      108           
  Lines       12245    12245           
  Branches     2267     2267           
=======================================
  Hits        10814    10814           
  Misses        902      902           
  Partials      529      529           

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