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

Bumps [rb-sys](https://github.com/oxidize-rb/rb-sys) from 0.9.26 to 0.9.28.
- [Release notes](https://github.com/oxidize-rb/rb-sys/releases)
- [Commits](oxidize-rb/rb-sys@v0.9.26...v0.9.28)

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

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

Author: dependabot[bot]

test/rubygems/test_gem_ext_cargo_builder/custom_name/Cargo.lock

@@ -7,4 +7,4 @@ edition = "2021"
 crate-type = ["cdylib"]
 
 [dependencies]
-rb-sys = { version = "0.9.26", features = ["gem"] }
+rb-sys = { version = "0.9.28", features = ["gem"] }