Bump actions/setup-python from 5 to 6 in the actions group (ipython#15005)

Bumps the actions group with 1 update:
[actions/setup-python](https://github.com/actions/setup-python).

Updates `actions/setup-python` from 5 to 6

Author: Carreau

.github/workflows/docs.yml

@@ -12,7 +12,7 @@ jobs:
     steps:
     - uses: actions/checkout@v5
     - name: Set up Python
-      uses: actions/setup-python@v5
+      uses: actions/setup-python@v6
       with:
         python-version: 3.x
     - name: Install Graphviz

.github/workflows/downstream.yml

@@ -31,7 +31,7 @@ jobs:
     steps:
     - uses: actions/checkout@v5
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v5
+      uses: actions/setup-python@v6
       with:
         python-version: ${{ matrix.python-version }}
     - name: Update Python installer

.github/workflows/mypy.yml

@@ -20,7 +20,7 @@ jobs:
     steps:
     - uses: actions/checkout@v5
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v5
+      uses: actions/setup-python@v6
       with:
         python-version: ${{ matrix.python-version }}
     - name: Install dependencies

.github/workflows/nightly-wheel-build.yml

@@ -15,7 +15,7 @@ jobs:
     steps:
       - uses: actions/checkout@v5
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: "3.13"
           cache: pip

.github/workflows/python-package.yml

@@ -22,7 +22,7 @@ jobs:
       with:
         fetch-depth: 0
     - name: Set up Python
-      uses: actions/setup-python@v5
+      uses: actions/setup-python@v6
       with:
         python-version: 3.x
     - name: Install dependencies

.github/workflows/ruff.yml

@@ -20,7 +20,7 @@ jobs:
     steps:
     - uses: actions/checkout@v5
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v5
+      uses: actions/setup-python@v6
       with:
         python-version: ${{ matrix.python-version }}
     - name: Install dependencies

.github/workflows/test.yml

@@ -59,7 +59,7 @@ jobs:
     steps:
     - uses: actions/checkout@v5
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v5
+      uses: actions/setup-python@v6
       with:
         python-version: ${{ matrix.python-version }}
         cache: pip