build(deps): bump rack-session in /gapic-generator-ads

Bumps [rack-session](https://github.com/rack/rack-session) from 2.1.1 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@v2.1.1...v2.1.2)

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

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

Author: dependabot[bot]

gapic-generator-ads/Gemfile.lock

@@ -109,8 +109,8 @@ GEM
       reline (>= 0.6.0)
     public_suffix (7.0.5)
     racc (1.8.1)
-    rack (3.2.5)
-    rack-session (2.1.1)
+    rack (3.2.6)
+    rack-session (2.1.2)
       base64 (>= 0.1.0)
       rack (>= 3.0.0)
     rack-test (2.2.0)