[Security] Bump ffi from 1.9.10 to 1.11.1

Bumps [ffi](https://github.com/ffi/ffi) from 1.9.10 to 1.11.1. **This update includes security fixes.**
- [Release notes](https://github.com/ffi/ffi/releases)
- [Changelog](https://github.com/ffi/ffi/blob/master/CHANGELOG.md)
- [Commits](ffi/ffi@1.9.10...1.11.1)

Gemfile.lock

@@ -158,7 +158,7 @@ GEM
     faraday-honeycomb (0.3.1)
       libhoney (>= 1.5.0)
     fastercsv (1.5.5)
-    ffi (1.9.10)
+    ffi (1.11.1)
     globalid (0.4.2)
       activesupport (>= 4.2.0)
     hashie (3.5.6)