Drop Intel macOS from release matrix; add concurrency + build timeout

GitHub's Intel (macos-13) runners are being deprecated and their queue is
unreliable, which blocked the v0.2.2 release. Ship macOS as Apple Silicon
only; Linux keeps x86_64 + aarch64. Also add a concurrency group so
re-pushing a tag cancels an in-flight run, and a 30m build timeout so a
capacity-starved runner fails fast instead of hanging for 24h.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: jeromechoo

.github/workflows/release.yml

@@ -11,10 +11,19 @@ on:
 permissions:
   contents: write
 
+# Re-pushing a tag (or re-dispatching) cancels an in-flight run for the same
+# ref so a stuck build can't pile up behind a newer attempt.
+concurrency:
+  group: release-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   build:
     name: Build ${{ matrix.target_os }}-${{ matrix.arch }}
     runs-on: ${{ matrix.runner }}
+    # Cap the wait so a capacity-starved runner fails this leg in minutes
+    # instead of hanging the release for GitHub's 24h queue limit.
+    timeout-minutes: 30
     strategy:
       fail-fast: false
       matrix:
@@ -28,9 +37,9 @@ jobs:
           - runner: ubuntu-22.04-arm
             target_os: linux
             arch: aarch64
-          - runner: macos-13        # Intel
-            target_os: darwin
-            arch: x86_64
+          # macOS is Apple Silicon only: GitHub's Intel (macos-13) runners are
+          # being deprecated and their queue is unreliable. Intel-Mac users can
+          # still `pip install diffbot-python`.
           - runner: macos-14        # Apple Silicon
             target_os: darwin
             arch: aarch64

README.md

@@ -204,7 +204,7 @@ This drops a `db` executable into `~/.local/bin` (ensure it is on your `PATH`).
 
 ### Standalone binary (no Python required)
 
-Every release also ships a self-contained `db` binary for Linux and macOS (x86_64 and aarch64/arm64) — no Python install needed. The installer detects your platform, verifies the SHA256 checksum, and installs (or upgrades) `db` into `~/.local/bin`:
+Every release also ships a self-contained `db` binary for Linux (x86_64 and aarch64) and macOS (Apple Silicon) — no Python install needed. The installer detects your platform, verifies the SHA256 checksum, and installs (or upgrades) `db` into `~/.local/bin`:
 
 ```bash
 curl -fsSL https://raw.githubusercontent.com/diffbot/diffbot-python/main/install.sh | sh