Build(deps): Bump actions/cache from 3 to 4

Bumps [actions/cache](https://github.com/actions/cache) from 3 to 4.
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](actions/cache@v3...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/functionaltests.yml

@@ -34,7 +34,7 @@ jobs:
           ini-values: opcache.fast_shutdown=0
 
       - name: "[1/5] Create composer project - Cache composer dependencies"
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: ~/.composer/cache
           key: php-${{ matrix.php-version }}-flow-${{ matrix.flow-version }}-composer-${{ hashFiles('composer.json') }}

.github/workflows/unittests.yml

@@ -27,7 +27,7 @@ jobs:
           ini-values: opcache.fast_shutdown=0
 
       - name: "[1/5] Create composer project - Cache composer dependencies"
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: ~/.composer/cache
           key: php-${{ matrix.php-version }}-flow-${{ matrix.flow-version }}-composer-${{ hashFiles('composer.json') }}