Bump ffi from 1.15.4 to 1.15.5 (#82)

Bumps [ffi](https://github.com/ffi/ffi) from 1.15.4 to 1.15.5.
- [Release notes](https://github.com/ffi/ffi/releases)
- [Changelog](https://github.com/ffi/ffi/blob/master/CHANGELOG.md)
- [Commits](ffi/ffi@v1.15.4...v1.15.5)

---
updated-dependencies:
- dependency-name: ffi
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

Gemfile.lock

@@ -10,7 +10,7 @@ GEM
   remote: https://rubygems.org/
   specs:
     diff-lcs (1.4.4)
-    ffi (1.15.4)
+    ffi (1.15.5)
     rake (13.0.6)
     rgeo (2.3.0)
     rgeo-geojson (2.1.1)