Replace resource.txt with resource.robot

Change-Id: I4d2afd35645880e33a31644cd717bbeae55666f0
Signed-off-by: Sandhya Somashekar <sansomas@in.ibm.com>
diff --git a/lib/certificate_utils.robot b/lib/certificate_utils.robot
index 6da2fb3..cb787b2 100755
--- a/lib/certificate_utils.robot
+++ b/lib/certificate_utils.robot
@@ -3,7 +3,7 @@
 
 Library        OperatingSystem
 Resource       rest_client.robot
-Resource       resource.txt
+Resource       resource.robot
 
 
 *** Keywords ***