Bump flipper from 0.25.4 to 0.26.0 (#4069)

Bumps [flipper](https://github.com/jnunemaker/flipper) from 0.25.4 to 0.26.0.
- [Release notes](https://github.com/jnunemaker/flipper/releases)
- [Changelog](https://github.com/jnunemaker/flipper/blob/main/Changelog.md)
- [Commits](flippercloud/flipper@v0.25.4...v0.26.0)

---
updated-dependencies:
- dependency-name: flipper
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

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

Gemfile.lock

@@ -161,15 +161,16 @@ GEM
     faraday_middleware (1.2.0)
       faraday (~> 1.0)
     ffi (1.15.5)
-    flipper (0.25.4)
-    flipper-active_record (0.25.2)
+    flipper (0.26.0)
+      concurrent-ruby (< 2)
+    flipper-active_record (0.26.0)
       activerecord (>= 4.2, < 8)
-      flipper (~> 0.25.2)
-    flipper-ui (0.25.2)
+      flipper (~> 0.26.0)
+    flipper-ui (0.26.0)
       erubi (>= 1.0.0, < 2.0.0)
-      flipper (~> 0.25.2)
+      flipper (~> 0.26.0)
       rack (>= 1.4, < 3)
-      rack-protection (>= 1.5.3, <= 2.3.0)
+      rack-protection (>= 1.5.3, <= 4.0.0)
       sanitize (< 7)
     formatador (1.1.0)
     fugit (1.7.2)