build: bump actions/cache from 2 to 2.1.5 (#2715)

Bumps [actions/cache](https://github.com/actions/cache) from 2 to 2.1.5.
- [Release notes](https://github.com/actions/cache/releases)
- [Commits](https://github.com/actions/cache/compare/v2...v2.1.5)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/deploy.yml

@@ -64,7 +64,7 @@ jobs:
 
       # Cache files between builds
       - name: Setup | Cache Cargo
-        uses: actions/cache@v2
+        uses: actions/cache@v2.1.5
         with:
           path: |
             ~/.cargo/registry