Add LUA linting

.drone.yml

@@ -16,8 +16,8 @@ steps:
   image: alpine
   commands:
     - apk update
-    - apk add --no-cache lua lua-dev luarocks
-    - luarocks install luacheck
+    - apk add --no-cache luarocks5.1
+    - luarocks-5.1 install luacheck
     - luacheck sources
 
 - name: build