Bump pdm-project/setup-pdm from 3 to 4 in the actions group (#366)

Bumps the actions group with 1 update: [pdm-project/setup-pdm](https://github.com/pdm-project/setup-pdm).


Updates `pdm-project/setup-pdm` from 3 to 4
- [Release notes](https://github.com/pdm-project/setup-pdm/releases)
- [Commits](pdm-project/setup-pdm@v3...v4)

---
updated-dependencies:
- dependency-name: pdm-project/setup-pdm
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: actions
...

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

Author: dependabot[bot]

.github/workflows/third_party.yml

@@ -61,7 +61,7 @@ jobs:
         with:
           path: typing-extensions-latest
       - name: Setup pdm for pydantic tests
-        uses: pdm-project/setup-pdm@v3
+        uses: pdm-project/setup-pdm@v4
         with:
           python-version: ${{ matrix.python-version }}
           allow-python-prereleases: true