ci: better pipeline config

- cancel builds in progress for a ref if another commit is pushed
- avoid multiple duplicate builds on pull request pushes
- allow workflow dispatch in a pinch

Author: flavorjones

.github/workflows/ci.yml

@@ -1,5 +1,19 @@
 name: CI
-on: [push, pull_request]
+concurrency:
+  group: "${{github.workflow}}-${{github.ref}}"
+  cancel-in-progress: true
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - main
+    tags:
+      - v*.*.*
+  pull_request:
+    types: [opened, synchronize]
+    branches:
+      - '*'
+
 jobs:
   tests:
     runs-on: ubuntu-latest

.github/workflows/gem-install.yml

@@ -1,5 +1,19 @@
 name: Native Gems
-on: [push, pull_request]
+concurrency:
+  group: "${{github.workflow}}-${{github.ref}}"
+  cancel-in-progress: true
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - main
+    tags:
+      - v*.*.*
+  pull_request:
+    types: [opened, synchronize]
+    branches:
+      - '*'
+
 jobs:
   package:
     strategy: