Switch to (up|down)load-artifact@v4

Author: hynek

.github/workflows/main.yml

@@ -32,12 +32,12 @@ jobs:
 
           python -Im tox
 
-      - name: "Upload coverage data"
-        uses: "actions/upload-artifact@v3"
+      - name: Upload coverage data
+        uses: actions/upload-artifact@v4
         with:
-          name: "coverage-data"
-          path: ".coverage.*"
-          if-no-files-found: "ignore"
+          name: coverage-data-${{ matrix.python-version }}
+          path: .coverage.*
+          if-no-files-found: ignore
 
   coverage:
     name: "Combine & check coverage."
@@ -54,9 +54,11 @@ jobs:
 
       - run: "python -Im pip install --upgrade coverage[toml]"
 
-      - uses: "actions/download-artifact@v3"
+      - name: Download coverage data
+        uses: actions/download-artifact@v4
         with:
-          name: "coverage-data"
+          pattern: coverage-data-*
+          merge-multiple: true
 
       - name: "Combine coverage"
         run: |
@@ -74,7 +76,7 @@ jobs:
           python -Im coverage report --fail-under=99
 
       - name: "Upload HTML report."
-        uses: "actions/upload-artifact@v3"
+        uses: "actions/upload-artifact@v4"
         with:
           name: "html-report"
           path: "htmlcov"