added usethesource repo to test pom.xml for depending on rascal

Author: jurgenvinju

src/it/simple-it/pom.xml

@@ -8,6 +8,12 @@
   <version>1.0-SNAPSHOT</version>
 
   <description>A simple Rascal file verifying the basic use case of the Rascal compiler Mojo.</description>
+  <repositories>
+      <repository>
+          <id>usethesource</id>
+          <url>https://releases.usethesource.io/maven/</url>
+      </repository>
+  </repositories>
 
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>