Update ffi

Author: JonRowe

Gemfile.lock

@@ -32,7 +32,7 @@ GEM
     fastimage (2.2.6)
     favicon_maker (1.3.1)
       docile (~> 1.1)
-    ffi (1.15.5)
+    ffi (1.17.0)
     haml (5.2.2)
       temple (>= 0.8.0)
       tilt