NSHM Unit tests

When running NSHM unit tests in pipeline, instead of running the hazard calculation in the junit test itself the hazard calculation is done by running a java class and writing out the results to JSON files.

src/test/java/gov/usgs/earthquake/nshmp/model/NshmTestUtils.java

@@ -12,8 +12,8 @@ import java.nio.file.Paths;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
-import java.util.Optional;
 import java.util.Map.Entry;
+import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
@@ -36,6 +36,7 @@ import gov.usgs.earthquake.nshmp.data.XySequence;
 import gov.usgs.earthquake.nshmp.geo.Location;
 import gov.usgs.earthquake.nshmp.gmm.Imt;
 import gov.usgs.earthquake.nshmp.site.NshmpSite;
+
 import io.swagger.v3.core.util.Yaml;
 
 /**
@@ -62,7 +63,7 @@ class NshmTestUtils {
     return new NshmModel(
         nshm,
         ModelLoader.load(nshm.modelPath()),
-        Executors.newFixedThreadPool(cores));
+        Executors.newFixedThreadPool(1));
   }
 
   /**