refactor: update caching key to use rust-toolchain.toml and improve package name extraction

.gitea/workflows/build.yaml

@@ -27,7 +27,7 @@ jobs:
             ~/.rustup
             ~/.cargo/registry
             ~/.cargo/git
-          key: ${{ runner.os }}-rustup-${{ hashFiles('**/Cargo.lock') }}
+          key: ${{ runner.os }}-rustup-${{ hashFiles('rust-toolchain.toml') }}
           restore-keys: |
             ${{ runner.os }}-rustup-
 
@@ -62,7 +62,19 @@ jobs:
         run: |
           set -e
           if [ -f Cargo.toml ]; then
-            PKG_NAME="$(sed -n 's/^name = \"\\(.*\\)\"/\\1/p' Cargo.toml | head -n 1)"
+            PKG_NAME="$(cargo metadata --no-deps --format-version=1 | python3 - <<'PY'
+import json
+import sys
+
+data = json.load(sys.stdin)
+for pkg in data.get("packages", []):
+    for target in pkg.get("targets", []):
+        if "bin" in target.get("kind", []):
+            print(target.get("name", ""))
+            raise SystemExit(0)
+print("")
+PY
+)"
           fi
           if [ -z "${PKG_NAME:-}" ]; then
             FULL="${GITHUB_REPOSITORY:-}"

rust-toolchain.toml

@@ -0,0 +1,2 @@
+[toolchain]
+channel = "1.90.0"