Bump the gh-actions group with 2 updates

Bumps the gh-actions group with 2 updates: [actions/checkout](https://github.com/actions/checkout) and [actions/cache](https://github.com/actions/cache).


Updates `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)

Updates `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](actions/cache@v4...v5)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: gh-actions
- dependency-name: actions/cache
  dependency-version: '5'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: gh-actions
...

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

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -11,7 +11,7 @@ jobs:
     build:
         runs-on: ubuntu-latest
         steps:
-          - uses: actions/checkout@v5
+          - uses: actions/checkout@v6
             with:
               # set fetch-depth to 0 for "git describe --tags" to work
               fetch-depth: 0
@@ -23,7 +23,7 @@ jobs:
               version-type: strict
 
           - name: Cache plt
-            uses: actions/cache@v4
+            uses: actions/cache@v5
             with:
               path: |
                 ~/.mix

.github/workflows/release.yml

@@ -15,7 +15,7 @@ jobs:
     build:
         runs-on: ubuntu-latest
         steps:
-          - uses: actions/checkout@v5
+          - uses: actions/checkout@v6
             with:
               # set fetch-depth to 0 for "git describe --tags" to work
               fetch-depth: 0