Bump dockerfile-rails from 1.6.25 to 1.7.0

Bumps [dockerfile-rails](https://github.com/fly-apps/dockerfile-rails) from 1.6.25 to 1.7.0.
- [Release notes](https://github.com/fly-apps/dockerfile-rails/releases)
- [Commits](fly-apps/dockerfile-rails@v1.6.25...v1.7.0)

---
updated-dependencies:
- dependency-name: dockerfile-rails
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Gemfile.lock

@@ -196,7 +196,7 @@ GEM
       thread_safe (~> 0.3, >= 0.3.1)
     diff-lcs (1.5.1)
     docile (1.4.1)
-    dockerfile-rails (1.6.25)
+    dockerfile-rails (1.7.0)
       rails (>= 3.0.0)
     dotenv (3.1.7)
     dotenv-rails (3.1.7)
@@ -394,7 +394,8 @@ GEM
     query_diet (0.7.2)
     racc (1.8.1)
     rack (3.1.8)
-    rack-session (2.0.0)
+    rack-session (2.1.0)
+      base64 (>= 0.1.0)
       rack (>= 3.0.0)
     rack-test (2.2.0)
       rack (>= 1.3)