Bump CCCL version to include cuda::std::span fix (#631)

This PR updates the CCCL version to include a fix for `cuda::std::span` which is required for cuCollections to work properly with CCCL 2.5.0. 

Most of the changes between the last CCCL version bump (#607) and this one were related to doc updates and unit test fixes, so I don't expect much functional impact for RAPIDS.

After this PR we likely have to bump the cuco version again to include the new changes.

### CCCL PR:

- NVIDIA/cccl#1836

### CUCO PR:

- NVIDIA/cuCollections#502

### RAPIDS PRs:

- [x] rapidsai/cudf#15986
  - [error during docs-build](https://github.com/rapidsai/cudf/actions/runs/9406273871/job/25911619452?pr=15946#step:9:2243) but seems unrelated
- [x] rapidsai/cugraph#4483
  - some CI jobs ran into a network timeout -> rerunning
- [x] rapidsai/cuml#5924
  - successful apart from some optional conda python tests
- [x] rapidsai/raft#2358
  - This one is weird as it [shows an error](https://github.com/rapidsai/raft/actions/runs/9475150045/job/26109283214?pr=2358#step:7:824) that is similar to the one we found in cuco when bumping the CCCL version to 2.5.0. However, we thought the problem was on cuco's end and pushed a fix that resolved the issue (see [Slack thread](https://nvidia.slack.com/archives/CCP05T27R/p1718060955876199))
- [x] rapidsai/rmm#1584

Authors:
  - Daniel Jünger (https://github.com/sleeepyjack)

Approvers:
  - Bradley Dice (https://github.com/bdice)

URL: #631

rapids-cmake/cpm/versions.json

@@ -9,7 +9,7 @@
  "version": "2.5.0",
  "git_shallow": false,
  "git_url": "https://github.com/NVIDIA/cccl.git",
- "git_tag": "fde1cf79bde6744b6739636f502b5edfefe302e1",
+ "git_tag": "e21d607157218540cd7c45461213fb96adf720b7",
  "patches": [
  {
  "file": "cccl/revert_pr_211.diff",