build(deps-dev): bump torchmetrics in /runtimes/mlflow (#1770)

Bumps [torchmetrics](https://github.com/Lightning-AI/torchmetrics) from 1.3.2 to 1.4.0.post0.
- [Release notes](https://github.com/Lightning-AI/torchmetrics/releases)
- [Changelog](https://github.com/Lightning-AI/torchmetrics/blob/master/CHANGELOG.md)
- [Commits](Lightning-AI/torchmetrics@v1.3.2...v1.4.0.post0)

---
updated-dependencies:
- dependency-name: torchmetrics
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

runtimes/mlflow/pyproject.toml

@@ -16,7 +16,7 @@ mlflow = "*"
 mlserver = {path = "../..", develop = true}
 torch = "2.2.1"
 pytorch-lightning = "2.2.4"
-torchmetrics = "1.3.2"
+torchmetrics = "1.4.0.post0"
 torchvision = "0.17.1"
 mlflow = "2.12.1"