Simmetrics Core uses a vulnerable version of Guava library 

Simmetrics Core uses a vulnerable version of Guava library:
```
<groupId>com.google.guava</groupId>
<artifactId>guava</artifactId>
<version>19.0</version>
```

See:

1. https://nvd.nist.gov/vuln/detail/CVE-2018-10237
2. https://nvd.nist.gov/vuln/detail/CVE-2020-8908


Please update to a newer version
