fix(ci): bump checkout 5 to 6, skip codecov updates for bot

Bumps [actions/checkout](https://github.com/actions/checkout) from 5 to
6.
- [Release notes](https://github.com/actions/checkout/releases)
-
[Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v5...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] <support@github.com>

fix(ci): skip codecov upload for dependabot PRs

Author: dependabot[bot]

.github/workflows/python-test.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Set up Python 3.12
         uses: actions/setup-python@v6
@@ -53,7 +53,7 @@ jobs:
           pytest --cov=persim --cov-report=xml
 
       - name: Upload coverage results
-        if: matrix.python-version == '3.12'
+        if: matrix.python-version == '3.12' && github.actor != 'dependabot[bot]'
         uses: codecov/codecov-action@v5
         with:
           token: ${{ secrets.CODECOV_TOKEN }}