chore(deps): bump actions/cache from 4 to 5

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](actions/cache@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] <[email protected]>

Author: dependabot[bot]

.github/workflows/buildtest.yml

@@ -70,7 +70,7 @@ jobs:
         run: |
           python3 -c "from pip._internal.locations import USER_CACHE_DIR; print('dir=' + USER_CACHE_DIR)" >> $GITHUB_OUTPUT
       - name: Set pip cache
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         with:
           path: ${{ steps.pip-cache.outputs.dir }}
           key: ${{ runner.os }}-pip-${{ hashFiles('**/requirements.txt') }}
@@ -169,7 +169,7 @@ jobs:
           New-Item $dir -ItemType Directory
           "dir=$($dir)" >> ${Env:GITHUB_OUTPUT}
       - name: Set files cache
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         with:
           path: ${{ steps.files.outputs.dir }}
           key: ${{ runner.os }}-64-files-${{ hashFiles('**/url.txt') }}
@@ -207,7 +207,7 @@ jobs:
         run: |
           python3 -c "from pip._internal.locations import USER_CACHE_DIR; print('dir=' + USER_CACHE_DIR)" >> ${Env:GITHUB_OUTPUT}
       - name: Set pip cache
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         with:
           path: ${{ steps.pip-cache.outputs.dir }}
           key: ${{ runner.os }}-pip-${{ hashFiles('**/requirements.txt') }}