Bump gradle-core from 3.1 to 6.0 in /meecrowave-gradle-plugin

Bumps gradle-core from 3.1 to 6.0.

---
updated-dependencies:
- dependency-name: org.gradle:gradle-core
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
diff --git a/meecrowave-gradle-plugin/pom.xml b/meecrowave-gradle-plugin/pom.xml
index cdaf7db..882fdb0 100644
--- a/meecrowave-gradle-plugin/pom.xml
+++ b/meecrowave-gradle-plugin/pom.xml
@@ -29,7 +29,7 @@
   <name>Meecrowave :: Gradle</name>
 
   <properties>
-    <gradle.version>3.1</gradle.version>
+    <gradle.version>6.0</gradle.version>
     <meecrowave.build.name>${project.groupId}.gradle</meecrowave.build.name>
   </properties>