ci: pin the platforms and Ruby versions of 36.x

.github/release-matrix.json

@@ -0,0 +1,12 @@
+{
+  "supported-ruby-platforms": [
+    "aarch64-linux",
+    "aarch64-linux-musl",
+    "arm64-darwin",
+    "x64-mingw-ucrt",
+    "x86_64-darwin",
+    "x86_64-linux",
+    "x86_64-linux-musl"
+  ],
+  "stable-ruby-versions": ["3.2", "3.3", "3.4"]
+}

.github/workflows/ci.yml

@@ -13,18 +13,12 @@ env:
   RSPEC_FORMATTER: doc
 
 jobs:
+  # Test the Ruby versions pinned in `.github/release-matrix.json`, resolved the
+  # same way as for releases.
   ci-data:
-    runs-on: ubuntu-latest
-    outputs:
-      result: ${{ steps.fetch.outputs.result }}
-    steps:
-      - id: fetch
-        uses: oxidize-rb/actions/fetch-ci-data@v1
-        with:
-          stable-ruby-versions: |
-              # See https://github.com/bytecodealliance/wasmtime-rb/issues/286
-              # for details.
-              exclude: [head]
+    uses: bytecodealliance/wasmtime-rb/.github/workflows/native-gem-matrix.yml@main
+    with:
+      snapshot: true
 
   ci:
     runs-on: ${{ matrix.os }}

ext/src/ruby_api/component/convert.rs

@@ -211,7 +211,7 @@ pub(crate) fn rb_to_component_val(
             let payload_val = match (&case.ty, payload_rb.is_nil()) {
                 (Some(ty), _) => rb_to_component_val(payload_rb, _store, ty)
                     .map(|val| Some(Box::new(val)))
-                    .map_err(|e| e.append(format!(" (variant value for \"{}\")", &name))),
+                    .map_err(|e| e.append(format!(" (variant value for \"{}\")", name))),
 
                 // case doesn't have payload and Variant#value *is nil*
                 (None, true) => Ok(None),

ext/src/ruby_api/engine.rs

@@ -90,7 +90,7 @@ impl Engine {
     pub fn new(args: &[Value]) -> Result<Self, Error> {
         let args = scan_args::scan_args::<(), (Option<Value>,), (), (), (), ()>(args)?;
         let (config,) = args.optional;
-        let config = config.and_then(|v| if v.is_nil() { None } else { Some(v) });
+        let config = config.filter(|v| !v.is_nil());
         let inner = match config {
             Some(config) => {
                 let config = RHash::try_convert(config).and_then(hash_to_config)?;

ext/src/ruby_api/instance.rs

@@ -43,10 +43,7 @@ impl Instance {
             scan_args::scan_args::<(Obj<Store>, &Module), (Option<Value>,), (), (), (), ()>(args)?;
         let (wrapped_store, module) = args.required;
         let mut context = wrapped_store.context_mut();
-        let imports = args
-            .optional
-            .0
-            .and_then(|v| if v.is_nil() { None } else { Some(v) });
+        let imports = args.optional.0.filter(|v| !v.is_nil());
 
         let imports: Vec<Extern> = match imports {
             Some(arr) => {