Database credentials are not retrieved

I am using your library with spring boot.
```
implementation("com.amazonaws.secretsmanager:aws-secretsmanager-jdbc:2.0.2")
```

I have the following settings in my `application.yaml`:
```
spring:
datasource:
driver-class-name: com.amazonaws.secretsmanager.sql.AWSSecretsManagerPostgreSQLDriver
url: jdbc-secretsmanager:postgresql://host:5432/database_name
user: secret_name
```

It seems that the library does not retrieve the credentials from the secret manager. When I run the spring boot application and I try to connect to the database I get the following error:
```
Could not open JPA EntityManager for transaction] with root cause

org.postgresql.util.PSQLException: The server requested SCRAM-based authentication, but no password was provided.
```

Start with the application.yaml datasource settings and reproduce the Spring Boot connection using aws-secretsmanager-jdbc 2.0.2. Trace why the PostgreSQL driver receives no password from the configured secret; done means the credentials are retrieved and the application connects without the SCRAM authentication error.

Written by the indexing model from the issue text.