re-adding the old junit:junit dep as solr-test-framework needs it

dhp-workflows/dhp-graph-provision/pom.xml

@@ -54,15 +54,18 @@
             <artifactId>spark-solr</artifactId>
         </dependency>
 
+        <!-- the solr-test-framework requires the old junit:junit test framework -->
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.12</version>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>org.apache.solr</groupId>
             <artifactId>solr-test-framework</artifactId>
             <scope>test</scope>
             <exclusions>
-                <exclusion>
-                    <groupId>junit</groupId>
-                    <artifactId>junit</artifactId>
-                </exclusion>
                 <exclusion>
                     <groupId>com.carrotsearch</groupId>
                     <artifactId>*</artifactId>