Bump actions/checkout from 4 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v4...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/build_wheels.yml

@@ -26,7 +26,7 @@ jobs:
 
     steps:
       - name: Checkout alphalens
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0
           fetch-tags: true

.github/workflows/conda_package.yml

@@ -20,7 +20,7 @@ jobs:
 
     steps:
       - name: Checkout alphalens-reloaded
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup miniconda3
         uses: conda-incubator/setup-miniconda@v3

.github/workflows/unit_tests.yml

@@ -21,7 +21,7 @@ jobs:
         python-version: [ '3.10', '3.11', '3.12', '3.13' ]
     steps:
       - name: Checkout alphalens
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v5