Bump astral-sh/setup-uv from 5 to 6 (#569)

Author: dependabot[bot]

.github/workflows/tests.yml

@@ -62,7 +62,7 @@ jobs:
               print(f"VIRTUALENV_PIP={pip.__version__}", file=io)
 
       - name: Install uv
-        uses: astral-sh/setup-uv@v5
+        uses: astral-sh/setup-uv@v6
 
       - name: Install Nox
         run: |
@@ -149,7 +149,7 @@ jobs:
           pip --version
 
       - name: Install uv
-        uses: astral-sh/setup-uv@v5
+        uses: astral-sh/setup-uv@v6
 
       - name: Install Nox
         run: |