Upgraded to v3.0.4 to fix incorrect plugin implementation that breaks…

… builds in Maven 3.4+

```
Unable to parse configuration of mojo org.codehaus.mojo:findbugs-maven-plugin:3.0.2:findbugs for parameter pluginArtifacts: Cannot assign configuration entry 'pluginArtifacts' with value '${plugin.artifacts}' of type java.util.Collections.UnmodifiableRandomAccessList to property of type java.util.ArrayList
```

pom.xml

@@ -300,7 +300,7 @@
                 <!-- Using FindBugs to prevent bugs that are identifiable by static analysis -->
                 <groupId>org.codehaus.mojo</groupId>
                 <artifactId>findbugs-maven-plugin</artifactId>
-                <version>3.0.2</version>
+                <version>3.0.4</version>
                 <configuration>
                     <onlyAnalyze>io.arivera.-</onlyAnalyze>
                     <fork>false</fork>