Update plugin and dependency versions

* Update `dependency-check-maven` to `6.0.5`
* Update `guava` (CVE-2020-8908)
* Update `spring` (CVE-2020-5421)
* Update `junit` version
* Update changelog

Related to #55

Author: vadeg

CHANGELOG.MD

@@ -6,6 +6,13 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+### Changed
+
+- Change base package from `de.zalando` to `org.zalando`
+- Update `postgresql` ([CVE-2020-13692](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-13692))
+- Update `guava` ([CVE-2020-8908](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-8908))
+- Update `spring` ([CVE-2020-5421](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-5421))
+
 ## [2.0.0] - 2017-08-04
 
 ### Added

pom.xml

@@ -61,7 +61,7 @@
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <maven.compiler.source>1.8</maven.compiler.source>
         <maven.compiler.target>1.8</maven.compiler.target>
-        <spring.version>5.2.5.RELEASE</spring.version>
+        <spring.version>5.2.12.RELEASE</spring.version>
         <postgresql.version>42.2.14</postgresql.version>
     </properties>
 
@@ -115,7 +115,7 @@
         <dependency>
             <groupId>com.google.guava</groupId>
             <artifactId>guava</artifactId>
-            <version>28.0-jre</version>
+            <version>30.1-jre</version>
         </dependency>
         <dependency>
             <groupId>javax.persistence</groupId>
@@ -133,7 +133,7 @@
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
             <scope>test</scope>
-            <version>4.12</version>
+            <version>4.13.1</version>
         </dependency>
         <dependency>
             <groupId>org.springframework</groupId>
@@ -198,7 +198,7 @@
             <plugin>
                 <groupId>org.owasp</groupId>
                 <artifactId>dependency-check-maven</artifactId>
-                <version>5.0.0</version>
+                <version>6.0.5</version>
                 <executions>
                     <execution>
                         <goals>