Fallback to dictionary/tuple for invalid attributes

Some headers contain keys which are invalid attribute names, see https://git.km3net.de/common/km3net-dataformat/-/issues/19#note_23531

This MR falls back to dictionaries and normal tuples in case of invalid entries.

CHANGELOG.rst

 Unreleased changes
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+* Fixes parsing error when a MC header contains invalid attribute names.
 
 Version 0
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