Update GitHub Actions to 2026 latest, fix release idempotency

- Bump setup-python v5 → v6, upload-artifact v4 → v7,
  download-artifact v4 → v8, ci.yml checkout v4 → v6
- gh release create falls back to gh release upload --clobber
  on re-runs so partial failures can be retried

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: ilyazub

.github/workflows/ci.yml

@@ -19,10 +19,10 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
 
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v5
+      uses: actions/setup-python@v6
       with:
         python-version: ${{ matrix.python-version }}
 

.github/workflows/release.yml

@@ -18,7 +18,7 @@ jobs:
     steps:
       - uses: actions/checkout@v6
 
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@v6
         with:
           python-version: ${{ matrix.python-version }}
 
@@ -43,7 +43,7 @@ jobs:
     steps:
       - uses: actions/checkout@v6
 
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@v6
         with:
           python-version: "3.13"
 
@@ -52,7 +52,7 @@ jobs:
           pip install build
           python -m build
 
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@v7
         with:
           name: dist
           path: dist/
@@ -66,20 +66,22 @@ jobs:
       contents: write
       packages: write
     steps:
-      - uses: actions/download-artifact@v4
+      - uses: actions/download-artifact@v8
         with:
           name: dist
           path: dist/
 
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@v6
         with:
           python-version: "3.13"
 
       - name: Create GitHub Release
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           GH_REPO: ${{ github.repository }}
-        run: gh release create ${{ github.ref_name }} dist/* --generate-notes
+        run: |
+          gh release create ${{ github.ref_name }} dist/* --generate-notes \
+            || gh release upload ${{ github.ref_name }} dist/* --clobber
 
       - name: Install twine
         run: pip install --upgrade pip twine
@@ -101,7 +103,7 @@ jobs:
     needs: [publish]
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@v6
         with:
           python-version: "3.13"