vtkDataReader: fix C++20 compat
Technically this is a breaking change, but this is documented as an internal function and C++20 doesn't support what this wants to do out-of-the-box.
Fixes: #18625 (closed)
Cc: @Neumann-A
Backport: release
Technically this is a breaking change, but this is documented as an internal function and C++20 doesn't support what this wants to do out-of-the-box.
Fixes: #18625 (closed)
Cc: @Neumann-A
Backport: release