Update pdm-project/setup-pdm action to v4 (#39)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/pypi.yml

@@ -52,7 +52,7 @@ jobs:
 
 
       - name: Setup PDM
-        uses: pdm-project/setup-pdm@v3
+        uses: pdm-project/setup-pdm@v4
         with:
           python-version: ${{ matrix.python-version }}
           cache: true

.github/workflows/tests.yml

@@ -42,7 +42,7 @@ jobs:
           version: latest
 
       - name: Setup PDM
-        uses: pdm-project/setup-pdm@v3
+        uses: pdm-project/setup-pdm@v4
         with:
           python-version: ${{ matrix.python-version }}
           cache: true