build: set version to 4.0.0-SNAPSHOT

Author: javier-godoy

pom.xml

@@ -3,7 +3,7 @@
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>com.flowingcode.vaadin.addons</groupId>
 	<artifactId>error-window-vaadin</artifactId>
-	<version>3.7.1-SNAPSHOT</version>
+	<version>4.0.0-SNAPSHOT</version>
 	<name>Error Window Add-on</name>
 	<description>Error handler that displays a dialog with exception information</description>
 	<url>https://www.flowingcode.com/en/open-source/</url>