Bump up version number to 3.1.0

Author: michel-kraemer

README.md

@@ -31,7 +31,7 @@ You may also use [Maven](https://maven.apache.org/) to download bson4jackson:
     <dependency>
         <groupId>de.undercouch</groupId>
         <artifactId>bson4jackson</artifactId>
-        <version>3.0.0</version>
+        <version>3.1.0</version>
     </dependency>
 </dependencies>
 ```
@@ -41,7 +41,7 @@ following snippet to your `build.gradle`:
 
 ```gradle
 dependencies {
-    implementation 'de.undercouch:bson4jackson:3.0.0'
+    implementation 'de.undercouch:bson4jackson:3.1.0'
 }
 ```
 

build.gradle

@@ -7,7 +7,7 @@ apply plugin: 'maven-publish'
 apply plugin: 'signing'
 apply plugin: 'java'
 
-version = '3.0.0'
+version = '3.1.0'
 group = 'de.undercouch'
 
 ext.isReleaseVersion = !version.endsWith("SNAPSHOT")