chore: remove vaadin prereleases repository

Author: javier-godoy

pom.xml

@@ -53,10 +53,6 @@
         <repository>
             <id>Vaadin Directory</id>
             <url>https://maven.vaadin.com/vaadin-addons</url>
-        </repository>
-        <repository>
-            <id>Vaadin prereleases</id>
-            <url>https://maven.vaadin.com/vaadin-prereleases</url>
         </repository>        
         <repository>
 			<id>FlowingCode Releases</id>