Bump actions/cache from 2 to 4

Bumps [actions/cache](https://github.com/actions/cache) from 2 to 4.
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](actions/cache@v2...v4)

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

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

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -16,7 +16,7 @@ jobs:
         java-version: 11
         distribution: temurin
     - name: Mount caches
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       with:
         path: |
           ~/.sbt

.github/workflows/release.yml

@@ -11,7 +11,7 @@ jobs:
     steps:
     - uses: actions/checkout@v1
     - name: Scala caches
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       with:
         path: |
           ~/.sbt