Bump rack-session from 2.0.0 to 2.1.2 (#24)

Bumps [rack-session](https://github.com/rack/rack-session) from 2.0.0 to 2.1.2.
- [Release notes](https://github.com/rack/rack-session/releases)
- [Changelog](https://github.com/rack/rack-session/blob/main/releases.md)
- [Commits](rack/rack-session@v2.0.0...v2.1.2)

---
updated-dependencies:
- dependency-name: rack-session
  dependency-version: 2.1.2
  dependency-type: indirect
...

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Author: dependabot[bot]

Gemfile.lock

@@ -86,8 +86,9 @@ GEM
     psych (5.1.2)
       stringio
     racc (1.8.1)
-    rack (3.1.21)
-    rack-session (2.0.0)
+    rack (3.2.6)
+    rack-session (2.1.2)
+      base64 (>= 0.1.0)
       rack (>= 3.0.0)
     rack-test (2.1.0)
       rack (>= 1.3)