Fixed typo in run_tests.sh file

Change-Id: If192b4c41c4ad136b9890810a46ddb083ac33ce2
diff --git a/tests/run_tests.sh b/tests/run_tests.sh
index ce315da..7bd7278 100755
--- a/tests/run_tests.sh
+++ b/tests/run_tests.sh
@@ -149,7 +149,7 @@
 }
 
 salt_run() {
-    [ -e ${VEN_DIR}/bin/activate ] && source ${VENV_DIR}/bin/activate
+    [ -e ${VENV_DIR}/bin/activate ] && source ${VENV_DIR}/bin/activate
     salt-call ${SALT_OPTS} $*
 }