v0.12.5

TensorKit v0.12.5

Diff since v0.12.4

This update includes various small fixes in the implementations of the AD rules.
Additionally, support was added for eigvals, svdvals, diag and diagm.

Merged pull requests:

• @non_differentiable TensorKit.id (#129) (@tangwei94)
• Add support for eigvals, svdvals and diag, diagm. (#130) (@lkdvos)
• small fix in the backward rule of norm (#131) (@tangwei94)
• Move FiniteDifferences support to package extension (#132) (@lkdvos)
• Refactor ChainRulesCoreExt into separate files (#133) (@lkdvos)
• Soften type restrictions on tsvd kwargs (#134) (@lkdvos)