Fix using supplied decoder for encrypted values (#23)

# Fix using supplied decoder for encrypted values

## ♻️ Current situation & Problem
There was an issue in the `read` implementation where the supplied
`decoder` was only used if the element wasn't encrypted. The other code
path was forgotten to be updated in #21.
This issue is fixed by this PR. 

## ⚙️ Release Notes 
* Fixed an issue where the supplied decoder wasn't used.


## 📚 Documentation
--


## ✅ Testing
--


## 📝 Code of Conduct & Contributing Guidelines 

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of
Conduct](https://github.com/StanfordSpezi/.github/blob/main/CODE_OF_CONDUCT.md)
and [Contributing
Guidelines](https://github.com/StanfordSpezi/.github/blob/main/CONTRIBUTING.md):
- [x] I agree to follow the [Code of
Conduct](https://github.com/StanfordSpezi/.github/blob/main/CODE_OF_CONDUCT.md)
and [Contributing
Guidelines](https://github.com/StanfordSpezi/.github/blob/main/CONTRIBUTING.md).

Sources/SpeziLocalStorage/LocalStorage.swift

@@ -161,7 +161,7 @@ public final class LocalStorage: Module, DefaultInitializable, EnvironmentAccess
             throw LocalStorageError.decryptionNotPossible
         }
 
-        return try JSONDecoder().decode(C.self, from: decryptedData)
+        return try decoder.decode(C.self, from: decryptedData)
     }