Fix Travis configuration formatting

Author: szarnyasg

.travis.yml

@@ -15,7 +15,7 @@ install: true
 script:
 - cp params-csv.ini params.ini
 - docker run --rm --mount type=bind,source="$(pwd)/",target="/opt/ldbc_snb_datagen/out" --mount type=bind,source="$(pwd)/params.ini",target="/opt/ldbc_snb_datagen/params.ini" ldbc/datagen
-- [[ `md5sum social_network/*.csv | sort | md5sum` == 'fa046e4c44e4c3e8f6858720c45d80ed  -' ]]
+- "[[ `md5sum social_network/*.csv | sort | md5sum` == 'fa046e4c44e4c3e8f6858720c45d80ed  -' ]]"
 - mkdir out
 - cp -r substitution_parameters out/
 notifications: