[rubygems/rubygems] Bump rb-sys

Bumps [rb-sys](https://github.com/oxidize-rb/rb-sys) from 0.9.67 to 0.9.68.
- [Release notes](https://github.com/oxidize-rb/rb-sys/releases)
- [Commits](https://github.com/oxidize-rb/rb-sys/compare/v0.9.67...v0.9.68)

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

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

test/rubygems/test_gem_ext_cargo_builder/rust_ruby_example/Cargo.lock

@@ -126,9 +126,9 @@ checksum = "19b17cddbe7ec3f8bc800887bab5e717348c95ea2ca0b1bf0837fb964dc67099"
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.47"
+version = "1.0.52"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5ea3d908b0e36316caf9e9e2c4625cdde190a7e6f440d794667ed17a1855e725"
+checksum = "1d0e1ae9e836cc3beddd63db0df682593d7e2d3d891ae8c9083d2113e1744224"
 dependencies = [
  "unicode-ident",
 ]
@@ -144,21 +144,22 @@ dependencies = [
 
 [[package]]
 name = "rb-sys"
-version = "0.9.67"
+version = "0.9.68"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6ef80f0a12d987db9c920c70ddf0bc2d9b59f921fc4d7998a68e48e59d179069"
+checksum = "4783528e031c3902524cfe685e0008d644e8b34bad4d1a19c1f39f4394d0777b"
 dependencies = [
  "rb-sys-build",
 ]
 
 [[package]]
 name = "rb-sys-build"
-version = "0.9.67"
+version = "0.9.68"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fbf55ef2409a2a05ede80b5fc88ce1c3bbe6f39960126a3d9c163670c7c60c98"
+checksum = "14c04474335dd597126d20fe90d94504b3582a30cbc36bc72c7d6ed3ef8cf168"
 dependencies = [
  "bindgen",
  "lazy_static",
+ "proc-macro2",
  "quote",
  "regex",
  "shell-words",

test/rubygems/test_gem_ext_cargo_builder/rust_ruby_example/Cargo.toml

@@ -7,4 +7,4 @@ edition = "2021"
 crate-type = ["cdylib"]
 
 [dependencies]
-rb-sys = "0.9.67"
+rb-sys = "0.9.68"