Bump hibernate-validator in /resteasy-dependencies-bom

Bumps [hibernate-validator](https://github.com/hibernate/hibernate-validator) from 6.0.18.Final to 6.0.20.Final.
- [Release notes](https://github.com/hibernate/hibernate-validator/releases)
- [Changelog](https://github.com/hibernate/hibernate-validator/blob/6.0.20.Final/changelog.txt)
- [Commits](hibernate/hibernate-validator@6.0.18.Final...6.0.20.Final)

---
updated-dependencies:
- dependency-name: org.hibernate.validator:hibernate-validator
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

resteasy-dependencies-bom/pom.xml

@@ -98,7 +98,7 @@
 
         <version.io.reactivex.rxjava2-rxjava>2.2.19</version.io.reactivex.rxjava2-rxjava>
         <version.org.reactivestreams>1.0.3</version.org.reactivestreams>
-        <version.org.hibernate.validator>6.0.18.Final</version.org.hibernate.validator>
+        <version.org.hibernate.validator>6.0.20.Final</version.org.hibernate.validator>
         <version.org.jboss.marshalling.jboss-marshalling>2.0.6.Final</version.org.jboss.marshalling.jboss-marshalling>
         <version.rest-assured>3.3.0</version.rest-assured>
         <version.org.springframework>5.3.7</version.org.springframework>