Bump dockerfile-rails from 1.5.10 to 1.5.12 (#85)

Bumps [dockerfile-rails](https://github.com/fly-apps/dockerfile-rails) from 1.5.10 to 1.5.12.
- [Release notes](https://github.com/fly-apps/dockerfile-rails/releases)
- [Commits](fly-apps/dockerfile-rails@v1.5.10...v1.5.12)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Garett Arrowood <[email protected]>

Gemfile.lock

@@ -113,7 +113,7 @@ GEM
       responders
       warden (~> 1.2.3)
     diff-lcs (1.5.0)
-    dockerfile-rails (1.5.10)
+    dockerfile-rails (1.5.12)
       rails (>= 3.0.0)
     dotenv (2.8.1)
     dotenv-rails (2.8.1)
@@ -162,7 +162,7 @@ GEM
     minitest (5.20.0)
     msgpack (1.7.2)
     mutex_m (0.1.2)
-    net-imap (0.4.2)
+    net-imap (0.4.3)
       date
       net-protocol
     net-pop (0.1.2)