Fixed typo in run_tests.sh file

Change-Id: I5b2570d2e46839ab89facb361373bb33c5bf23e7
diff --git a/tests/run_tests.sh b/tests/run_tests.sh
index f6d5e40..0d29e9d 100755
--- a/tests/run_tests.sh
+++ b/tests/run_tests.sh
@@ -125,7 +125,7 @@
 }
 
 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} $*
 }