Prepare release 3.1.3

Author: greenrobot-team

README.md

@@ -13,7 +13,7 @@
 [ObjectBox](https://objectbox.io/) is a superfast object-oriented Java database with strong relation support and easy-to-use native language APIs.
 ObjectBox is embedded into your Android, Linux, macOS, or Windows app.
 
-**Latest version: [3.1.2 (2022/02/21)](https://docs.objectbox.io/#objectbox-changelog)**
+**Latest version: [3.1.3 (2022/05/10)](https://docs.objectbox.io/#objectbox-changelog)**
 
 ❤ **Your opinion matters to us!** Please fill in this 2-minute [Anonymous Feedback Form](https://forms.gle/bdktGBUmL4m48ruj7).
 
@@ -67,7 +67,7 @@ For Android projects, add the ObjectBox Gradle plugin to your root `build.gradle
 
 ```groovy
 buildscript {
-    ext.objectboxVersion = "3.1.2"
+    ext.objectboxVersion = "3.1.3"
     repositories {        
         mavenCentral()    
     }

build.gradle

@@ -2,7 +2,7 @@ buildscript {
     ext {
         // Typically, only edit those two:
         def objectboxVersionNumber = '3.1.3' // without "-SNAPSHOT", e.g. '2.5.0' or '2.4.0-RC'
-        def objectboxVersionRelease = false  // set to true for releasing to ignore versionPostFix to avoid e.g. "-dev" versions
+        def objectboxVersionRelease = true  // set to true for releasing to ignore versionPostFix to avoid e.g. "-dev" versions
 
         // version post fix: '-<value>' or '' if not defined; e.g. used by CI to pass in branch name
         def versionPostFixValue = project.findProperty('versionPostFix')