Update .whitesource file with SAST scan settings for master

Author: LiyangW

.whitesource

@@ -1,5 +1,8 @@
-
 {
-  "settingsInheritedFrom": "ibm-skills-network/mend-config@main"
-}
-
+  "settingsInheritedFrom": "ibm-skills-network/mend-config@main",
+  "scanSettingsSAST": {
+    "baseBranches": [
+      "master"
+    ]
+  }
+}