Bump actions/cache from 5 to 6 in /.github/workflows

Bumps [actions/cache](https://github.com/actions/cache) from 5 to 6.
- [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/v5...v6)

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

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

.github/workflows/alpha.yml

@@ -95,7 +95,7 @@ jobs:
 
       - name: Cache NuGet packages
         if: ${{ needs.select-runner.outputs.runner == 'windows-latest' }}
-        uses: actions/cache@v5
+        uses: actions/cache@v6
         with:
           path: ~/.nuget/packages
           key: ${{ runner.os }}-nuget-${{ hashFiles('**/Snap.Hutao.csproj') }}

.github/workflows/canary.yml

@@ -59,7 +59,7 @@ jobs:
 
       - name: Cache NuGet packages
         if: ${{ steps.merge.outputs.continue == 'true' }}
-        uses: actions/cache@v5
+        uses: actions/cache@v6
         with:
           path: ~/.nuget/packages
           key: ${{ runner.os }}-nuget-${{ hashFiles('**/Snap.Hutao.csproj') }}