Bump ffi from 1.9.6 to 1.12.2

Bumps [ffi](https://github.com/ffi/ffi) from 1.9.6 to 1.12.2.
- [Release notes](https://github.com/ffi/ffi/releases)
- [Changelog](https://github.com/ffi/ffi/blob/master/CHANGELOG.md)
- [Commits](ffi/ffi@v1.9.6...1.12.2)

Signed-off-by: dependabot[bot] <support@github.com>

Gemfile.lock

@@ -20,7 +20,7 @@ GEM
     colorator (0.1)
     execjs (2.2.2)
     fast-stemmer (1.0.2)
-    ffi (1.9.6)
+    ffi (1.12.2)
     gemoji (2.1.0)
     github-pages (32)
       RedCloth (= 4.2.9)