Bump Kani version to 0.56.0 (model-checking#3581)

Bump our crates version and exclude `charon` from our workspace
(otherwise building the workspace wouldn't work). See my comment for the
original notes.

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 and MIT licenses.

CHANGELOG.md

@@ -4,6 +4,27 @@ This file contains notable changes (e.g. breaking changes, major changes, etc.)
 
 This file was introduced starting Kani 0.23.0, so it only contains changes from version 0.23.0 onwards.
 
+## [0.56.0]
+
+### Breaking Changes
+
+* Remove obsolete linker options (`--mir-linker` and `--legacy-linker`) by @zhassan-aws in https://github.com/model-checking/kani/pull/3559
+* Deprecate `kani::check` by @celinval in https://github.com/model-checking/kani/pull/3557
+
+### What's Changed
+
+* Enable stubbing and function contracts for primitive types by @celinval in https://github.com/model-checking/kani/pull/3496
+* Instrument validity checks for pointer to reference casts for slices and str's by @zhassan-aws in https://github.com/model-checking/kani/pull/3513
+* Fail compilation if `proof_for_contract` is added to generic function by @carolynzech in https://github.com/model-checking/kani/pull/3522
+* Fix storing coverage data in cargo projects by @adpaco-aws in https://github.com/model-checking/kani/pull/3527
+* Add experimental API to generate arbitrary pointers by @celinval in https://github.com/model-checking/kani/pull/3538
+* Running `verify-std` no longer changes Cargo files by @celinval in https://github.com/model-checking/kani/pull/3577
+* Add an LLBC backend by @zhassan-aws in https://github.com/model-checking/kani/pull/3514
+* Rust toolchain upgraded to nightly-2024-10-03 by @qinheping @tautschnig @celinval
+* CBMC upgraded to 6.3.1 by @tautschnig in https://github.com/model-checking/kani/pull/3537
+
+**Full Changelog**: https://github.com/model-checking/kani/compare/kani-0.55.0...kani-0.56.0
+
 ## [0.55.0]
 
 ### Major/Breaking Changes