build(deps): bump actions/cache from 4 to 6

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

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

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/lint.yaml

@@ -24,14 +24,14 @@ jobs:
       - name: Install pre-commit
         run: uv sync -U --group lint
 
-      - uses: actions/cache@v4
+      - uses: actions/cache@v6
         with:
           path: .mypy_cache
           key: ${{ runner.os }}-mypy-${{ hashFiles('pyproject.toml') }}
           restore-keys: |
             ${{ runner.os }}-mypy-
 
-      - uses: actions/cache@v4
+      - uses: actions/cache@v6
         with:
           path: ~/.cache/pre-commit
           key: ${{ runner.os }}-pre-commit-${{ hashFiles('.pre-commit-config.yaml') }}