chore: add vaadin-dev-server to javadoc generation

Author: ZheSun88

scripts/generator/templates/template-vaadin-platform-javadoc-pom.xml

@@ -106,6 +106,12 @@
                     <version>${flow.version}</version>
                     <scope>provided</scope>
                 </dependency>
+                <dependency>
+                    <groupId>com.vaadin</groupId>
+                    <artifactId>vaadin-dev-server</artifactId>
+                    <version>${flow.version}</version>
+                    <scope>provided</scope>
+                </dependency>
                 <dependency>
                     <groupId>com.vaadin</groupId>
                     <artifactId>vaadin-spring</artifactId>