Update nimbus

[Garandor]

Description

This change removes AuthorFilterAPI runtime API as a result of
moonbeam-foundation/nimbus@17ba75f

Our client was already not using this API so there should be no impact.

There are no further functional changes to the previous v3.4.3 tag (run git diff v3.4.3..v4.0.0 to verify)

It also changes us to a simplified branch structure on nimbus.

• upstreamable: branched off from main. Contains changes we can eventually upstream
• manta: branched off from upstreamable. Manta-specific changes that we likely won't upstream

the v4.0.0 tag this PR uses and all future tags always point to the manta branch, which will get changes from main merged in periodically.

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Before we can approve this PR for merge, please make sure that all the following items have been checked off:

• Linked to Github issue with discussion and accepted design OR have an explanation in the PR that describes this work.
• Added one label out of the L- group to this PR
• Added one or more labels from the A- and C- groups to this PR
• Explicitly labelled A-calamari, A-dolphin and/or A-manta if your changes are meant for/impact either of these (CI depends on it)
• This PR is targeted against the current Milestone ( otherwise discuss if it can be added in time)
• Re-reviewed Files changed in the Github PR explorer.

Situational Notes:

• If adding functionality, write unit tests!
• If importing a new pallet, choose a proper module index for it, and allow it in BaseFilter. Ensure every extrinsic works from front-end. If there's corresponding tool, ensure both work for each other.
• If needed, update our Javascript/Typescript APIs. These APIs are officially used by exchanges or community developers.
• If modifying existing runtime storage items, make sure to implement storage migrations for the runtime and test them with try-runtime. This includes migrations inherited from upstream changes, and you can search the diffs for modifications of #[pallet::storage] items to check for any.
• If runtime changes, need to update the version numbers properly:
  • authoring_version: The version of the authorship interface. An authoring node will not attempt to author blocks unless this is equal to its native runtime.
  • spec_version: The version of the runtime specification. A full node will not attempt to use its native runtime in substitute for the on-chain Wasm runtime unless all of spec_name, spec_version, and authoring_version are the same between Wasm and native.
  • impl_version: The version of the implementation of the specification. Nodes are free to ignore this; it serves only as an indication that the code is different; as long as the other two versions are the same then while the actual code may be different, it is nonetheless required to do the same thing. Non-consensus-breaking optimizations are about the only changes that could be made which would result in only the impl_version changing.
  • transaction_version: The version of the extrinsics interface. This number must be updated in the following circumstances: extrinsic parameters (number, order, or types) have been changed; extrinsics or pallets have been removed; or the pallet order in the construct_runtime! macro or extrinsic order in a pallet has been changed. You can run the metadata_diff.yml workflow for help. If this number is updated, then the spec_version must also be updated
• Verify benchmarks & weights have been updated for any modified runtime logics