[rubygems/rubygems] Bump rb-sys in /test/rubygems/test_gem_ext_cargo_builder/custom_name

Bumps [rb-sys](https://github.com/oxidize-rb/rb-sys) from 0.9.15 to 0.9.18.
- [Release notes](https://github.com/oxidize-rb/rb-sys/releases)
- [Commits](https://github.com/oxidize-rb/rb-sys/compare/v0.9.15...v0.9.18)

---
updated-dependencies:
- dependency-name: rb-sys
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

https://github.com/rubygems/rubygems/commit/a862203683

test/rubygems/test_gem_ext_cargo_builder/custom_name/Cargo.lock

@@ -160,9 +160,9 @@ dependencies = [
 
 [[package]]
 name = "rb-sys"
-version = "0.9.15"
+version = "0.9.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "104c5bcb9fa23bf3823124c003c516b22664fef50c4a481ff2d0e21b76e0f92c"
+checksum = "0ebbf80acc7a283f70eaeecde5eca8d503e0aaf23f737117398328048cd70077"
 dependencies = [
  "bindgen",
  "linkify",
@@ -171,9 +171,9 @@ dependencies = [
 
 [[package]]
 name = "rb-sys-build"
-version = "0.9.15"
+version = "0.9.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4cdf919b75ba95aa480159f3b20070cbec110d6c8a7af86b35844270069a4cb3"
+checksum = "d48277d27ff861590af07c8e1fd76de3aff5a37a227b745a4f42f40f914e62bc"
 dependencies = [
  "regex",
  "shell-words",

test/rubygems/test_gem_ext_cargo_builder/custom_name/Cargo.toml

@@ -7,4 +7,4 @@ edition = "2021"
 crate-type = ["cdylib"]
 
 [dependencies]
-rb-sys = { version = "0.9.15", features = ["gem"] }
+rb-sys = { version = "0.9.18", features = ["gem"] }