lts-check-last-commit: using https for API call

sometimes the JOB_URL environment variable will be 'http'
instead of 'https'. It results in the curl call failure.
Force to use https in the API call to fix the issue

Change-Id: I68130da6e0941d1ca0d81e34305541e1f5e4d5e5
Signed-off-by: Arthur She <arthur.she@linaro.org>
diff --git a/scripts/lts-check-last-commit.sh b/scripts/lts-check-last-commit.sh
index b9d66f9..574c306 100755
--- a/scripts/lts-check-last-commit.sh
+++ b/scripts/lts-check-last-commit.sh
@@ -3,6 +3,7 @@
 set -ex
 
 last_build=$((${BUILD_NUMBER}-1))
+JOB_URL=${JOB_URL//http:/https:}
 API_URL="${JOB_URL}/${last_build}/api/json"
 
 TO_BUILD_FILE="${WORKSPACE}/TO_BUILD"