build(deps): bump actions/cache from 2.1.6 to 2.1.7

Bumps [actions/cache](https://github.com/actions/cache) from 2.1.6 to 2.1.7.
- [Release notes](https://github.com/actions/cache/releases)
- [Commits](actions/cache@v2.1.6...v2.1.7)

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

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

.github/workflows/build.yml

@@ -13,7 +13,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2.4.0
 
-      - uses: actions/cache@v2.1.6
+      - uses: actions/cache@v2.1.7
         with:
           path: |
             ~/.cargo/registry
@@ -31,7 +31,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2.4.0
 
-      - uses: actions/cache@v2.1.6
+      - uses: actions/cache@v2.1.7
         with:
           path: |
             ~/.cargo/registry
@@ -64,7 +64,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2.4.0
 
-      - uses: actions/cache@v2.1.6
+      - uses: actions/cache@v2.1.7
         with:
           path: |
             ~/.cargo/registry