build: set version to 3.0.0-SNAPSHOT

Author: javier-godoy

pom.xml

@@ -3,7 +3,7 @@
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>com.flowingcode.vaadin.addons</groupId>
 	<artifactId>twincolgrid</artifactId>
-	<version>2.9.3-SNAPSHOT</version>
+	<version>3.0.0-SNAPSHOT</version>
 	<name>TwinColGrid add-on</name>
     <properties>
         <vaadin.version>14.8.20</vaadin.version>