build(deps): Bump bigdecimal from 3.1.7 to 3.1.8

Bumps [bigdecimal](https://github.com/ruby/bigdecimal) from 3.1.7 to 3.1.8.
- [Release notes](https://github.com/ruby/bigdecimal/releases)
- [Changelog](https://github.com/ruby/bigdecimal/blob/master/CHANGES.md)
- [Commits](ruby/bigdecimal@v3.1.7...v3.1.8)

---
updated-dependencies:
- dependency-name: bigdecimal
  dependency-type: indirect
  update-type: version-update:semver-patch
...

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

Gemfile.lock

@@ -94,7 +94,7 @@ GEM
       erubi (>= 1.0.0)
       rack (>= 0.9.0)
       rouge (>= 1.0.0)
-    bigdecimal (3.1.7)
+    bigdecimal (3.1.8)
     bindex (0.8.1)
     binding_of_caller (1.0.1)
       debug_inspector (>= 1.2.0)