Update pytorch-lightning requirement in /e2e/pytorch-lightning (#2751)

Updates the requirements on [pytorch-lightning](https://github.com/Lightning-AI/lightning) to permit the latest version.
- [Release notes](https://github.com/Lightning-AI/lightning/releases)
- [Commits](Lightning-AI/pytorch-lightning@1.6.0...2.1.3)

---
updated-dependencies:
- dependency-name: pytorch-lightning
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Taner Topal <[email protected]>

e2e/pytorch-lightning/pyproject.toml

@@ -11,5 +11,5 @@ authors = ["The Flower Authors <[email protected]>"]
 [tool.poetry.dependencies]
 python = "^3.8"
 flwr = { path = "../../", develop = true, extras = ["simulation"] }
-pytorch-lightning = "1.6.0"
+pytorch-lightning = "2.1.3"
 torchvision = "0.14.1"