Bump actions/upload-artifact from 4 to 6 (#501)

Author: dependabot[bot]

.github/workflows/docs.yml

@@ -114,7 +114,7 @@ jobs:
 
       # Store the docs as a build artifact so we can deploy it later
       - name: Upload HTML documentation as an artifact
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: docs-${{ github.sha }}
           path: doc/_build/html

.github/workflows/pypi.yml

@@ -79,7 +79,7 @@ jobs:
       - name: Upload archives as artifacts
         # Only if not a pull request
         if: success() && github.event_name != 'pull_request'
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: pypi-${{ github.sha }}
           path: dist

.github/workflows/test.yml

@@ -153,7 +153,7 @@ jobs:
         run: coverage xml
 
       - name: Upload coverage report as an artifact
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: coverage_${{ matrix.os }}_${{ matrix.dependencies }}
           path: ./coverage.xml