Add OpenBSD to the CI

Author: Thomasdezeeuw

.github/workflows/ci.yaml

@@ -55,6 +55,7 @@ jobs:
         - aarch64-apple-tvos
         - aarch64-apple-visionos
         - aarch64-apple-watchos
+        - x86_64-unknown-openbsd
     steps:
     - uses: actions/checkout@v6
     - uses: dtolnay/rust-toolchain@nightly