Add pluginRepository to test/pom.xml (#11015)

test/pom.xml

@@ -49,6 +49,19 @@
         </repository>
     </repositories>
 
+    <pluginRepositories>
+        <pluginRepository>
+            <id>vaadin-snapshots</id>
+            <url>https://oss.sonatype.org/content/repositories/vaadin-snapshots/</url>
+            <releases>
+                <enabled>false</enabled>
+            </releases>
+            <snapshots>
+                <enabled>true</enabled>
+            </snapshots>
+        </pluginRepository>
+    </pluginRepositories>
+
     <dependencyManagement>
         <dependencies>
             <dependency>