message: Fix clippy warning on unneeded lifetime
  It's strange that an unrelated change caused clippy to detect this one.
  Or maybe it's a rust version bump?
diff: @@ -1517,11 +1517,11 @@ where
  /// This iterator yields mutable sparse vector views for each outer
  /// dimension. Only the non-zero values can be modified, the
  /// structure is kept immutable.
  - pub fn outer_iterator_mut<'a>(
  - &'a mut self,
  - ) -> impl std::iter::DoubleEndedIterator<Item = CsVecViewMutI<'a, N, I>>
  - + std::iter::ExactSizeIterator<Item = CsVecViewMutI<'a, N, I>>
  - + 'a {
  + pub fn outer_iterator_mut(
  + &mut self,
  + ) -> impl std::iter::DoubleEndedIterator<Item = CsVecViewMutI<N, I>>
  + + std::iter::ExactSizeIterator<Item = CsVecViewMutI<N, I>>
  + + '_ {
  let inner_dim = self.inner_dims();
  let indices = &self.indices[..];
  let data_ptr: *mut N = self.data.as_mut_ptr();
  