chore: prepare release v0.4.0

pom.xml

@@ -1,11 +1,10 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
 
     <groupId>io.github.nramc</groupId>
     <artifactId>geojson4j</artifactId>
-    <version>0.3.1-SNAPSHOT</version>
+    <version>0.4.0</version>
 
     <name>geojson4j</name>
     <description>
@@ -38,7 +37,7 @@
         <url>https://github.com/nramc/geojson4j</url>
         <connection>scm:git:https://github.com/nramc/geojson4j.git</connection>
         <developerConnection>scm:git:https://github.com/nramc/geojson4j.git</developerConnection>
-        <tag>HEAD</tag>
+        <tag>v0.4.0</tag>
     </scm>
     <distributionManagement>
         <repository>