Update release workflow. (#3)

Author: bckohan

.github/workflows/release.yml

@@ -16,7 +16,7 @@ jobs:
     steps:
     - uses: actions/checkout@v4
     - name: Set up Python
-      uses: actions/setup-python@v4
+      uses: actions/setup-python@v5
       with:
         python-version: "3.x"
     - name: Install pypa/build
@@ -25,7 +25,7 @@ jobs:
     - name: Build a binary wheel and a source tarball
       run: python3 -m build
     - name: Store the distribution packages
-      uses: actions/upload-artifact@v3
+      uses: actions/upload-artifact@v4
       with:
         name: python-package-distributions
         path: dist/
@@ -44,7 +44,7 @@ jobs:
       id-token: write  # IMPORTANT: mandatory for trusted publishing
     steps:
     - name: Download all the dists
-      uses: actions/download-artifact@v3
+      uses: actions/download-artifact@v4
       with:
         name: python-package-distributions
         path: dist/
@@ -65,7 +65,7 @@ jobs:
 
     steps:
     - name: Download all the dists
-      uses: actions/download-artifact@v3
+      uses: actions/download-artifact@v4
       with:
         name: python-package-distributions
         path: dist/
@@ -96,6 +96,7 @@ jobs:
 
   publish-to-testpypi:
     name: Publish Python 🐍 distribution 📦 to TestPyPI
+    if: startsWith(github.ref, 'refs/tags/')  # only publish to TestPyPI on tag pushes
     needs:
     - build
     runs-on: ubuntu-latest
@@ -109,7 +110,7 @@ jobs:
 
     steps:
     - name: Download all the dists
-      uses: actions/download-artifact@v3
+      uses: actions/download-artifact@v4
       with:
         name: python-package-distributions
         path: dist/