Issue paypal#323 - upgrade TestNG version to 6.9.12

Author: ILikeToNguyen

pom.xml

@@ -19,7 +19,7 @@
         <iosdriver.version>0.6.5</iosdriver.version>
         <selendroid.version>0.17.0</selendroid.version>
         <appium.version>3.4.1</appium.version>
-        <testng.version>6.9.10</testng.version>
+        <testng.version>6.9.12</testng.version>
         <snakeyaml.version>1.15</snakeyaml.version>
         <htmlunit.version>2.20</htmlunit.version>
         <project.bom.version>${project.version}</project.bom.version>