Bump actions/cache from 4 to 5 (#365)

Bumps [actions/cache](https://github.com/actions/cache) from 4 to 5.
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](https://github.com/actions/cache/compare/v4...v5)

---
updated-dependencies:
- dependency-name: actions/cache
  dependency-version: '5'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/main.yml

@@ -21,14 +21,14 @@ jobs:
     steps:
     - uses: actions/checkout@v6
     - name: Cache pip
-      uses: actions/cache@v4
+      uses: actions/cache@v5
       with:
         path: ~/.cache/pip
         key: ${{ runner.os }}-pip-${{ hashFiles('**/requirements.txt') }}
         restore-keys: |
           ${{ runner.os }}-pip-
     - name: Cache PlatformIO
-      uses: actions/cache@v4
+      uses: actions/cache@v5
       with:
         path: ~/.platformio
         key: ${{ runner.os }}-${{ hashFiles('**/lockfiles') }}