fix: Add operator backward warnings

Context

Fix warnings introduced in !137 (merged), where some parameters of the Add backward kernels were unused.

changed milestone to %aidge v0.6.0

requested review from @pineapple

assigned to @jeromeh

added StatusReview Ready TopicOperator labels

changed target branch from main to dev

changed title from fix: Add operatator backward warnings to fix: Add operator backward warnings

mentioned in merge request !138 (merged)

added Fix 🔥🔥 label

approved this merge request

mentioned in commit 4cea3405

merged

mentioned in merge request !144 (closed)