chore(deps-dev): 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: direct:development
  update-type: version-update:semver-patch
...

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

Gemfile.lock

@@ -12,7 +12,7 @@ GEM
   specs:
     ansi (1.5.0)
     ast (2.4.2)
-    bigdecimal (3.1.7)
+    bigdecimal (3.1.8)
     builder (3.2.4)
     debug (1.9.2)
       irb (~> 1.10)