Upgrade to Log4J 2.17.1

The pom.xml file shows that java-sparkpost is at Log4J 2.17.0
```xml
<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-core</artifactId>
    <version>2.17.0</version>
</dependency>
```

Can this bumped to Log4J 2.17.1? The new version is the latest to address CVE-2021-44228