ci: upgrade actions/{upload,download}-artifact to v4 (#49)

Upgraded upload/download artifact GitHub actions to v4, as v3 will shortly stop working.

Author: ianroberts

.github/workflows/publish.yml

@@ -25,7 +25,7 @@ jobs:
       - name: Build
         run: poetry build
       - name: Store distribution packages
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: python-package-distributions
           path: dist/
@@ -41,7 +41,7 @@ jobs:
       id-token: write
     steps:
       - name: Download distribution packages
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: python-package-distributions
           path: dist/
@@ -59,7 +59,7 @@ jobs:
 
     steps:
     - name: Download distribution packages
-      uses: actions/download-artifact@v3
+      uses: actions/download-artifact@v4
       with:
         name: python-package-distributions
         path: dist/