Problem:
```
--- FAIL: TestMemCachedPersist (0.07s)
--- FAIL: TestMemCachedPersist/BoltDBStore (0.07s)
testing.go:894: TempDir RemoveAll cleanup: remove C:\Users\Anna\AppData\Local\Temp\TestMemCachedPersist_BoltDBStore294966711\001\test_bolt_db: The process cannot access the file because it is being used by another process.
```
Solution:
Release the resources occupied by the DB.