Publish tagged releases for mise installation

Package the script and license in a tar archive with a bin directory so
mise can install it without asset or path options.  Check syntax and
executable permissions before publishing, document installation, and keep
pinned actions updated with Dependabot.

Author: knu

.github/dependabot.yml

@@ -0,0 +1,10 @@
+version: 2
+updates:
+  - package-ecosystem: github-actions
+    directory: /
+    schedule:
+      interval: weekly
+    groups:
+      github-actions:
+        patterns:
+          - '*'

.github/workflows/release.yml

@@ -0,0 +1,51 @@
+name: Release
+
+on:
+  push:
+    tags:
+      - 'v*'
+
+permissions: {}
+
+concurrency:
+  group: release-${{ github.ref }}
+  cancel-in-progress: false
+
+jobs:
+  release:
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    permissions:
+      contents: write
+    steps:
+      - name: Harden runner
+        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
+        with:
+          egress-policy: audit
+
+      - name: Check out source
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          persist-credentials: false
+
+      - name: Check release asset
+        run: |
+          test -x git-delete-merged
+          sh -n git-delete-merged
+
+      - name: Package release
+        env:
+          TAG: ${{ github.ref_name }}
+        run: |
+          package_dir=$(mktemp -d "$RUNNER_TEMP/package.XXXXXX")
+          mkdir "$package_dir/bin"
+          install -m 755 git-delete-merged "$package_dir/bin/git-delete-merged"
+          cp LICENSE "$package_dir/LICENSE"
+          tar -czf "$RUNNER_TEMP/git-delete-merged-${TAG#v}.tar.gz" -C "$package_dir" bin LICENSE
+
+      - name: Publish release
+        env:
+          GH_TOKEN: ${{ github.token }}
+          GH_REPO: ${{ github.repository }}
+          TAG: ${{ github.ref_name }}
+        run: gh release create "$TAG" "$RUNNER_TEMP/git-delete-merged-${TAG#v}.tar.gz" --verify-tag --generate-notes

README.md

@@ -14,8 +14,14 @@ remote branch to have been deleted.
 
 ## Installation
 
-Put `git-delete-merged` somewhere on your `PATH`.  Git then also
-accepts it as `git delete-merged`.
+Install with [mise](https://mise.jdx.dev/):
+
+```sh
+mise use -g github:gitbits/git-delete-merged@latest
+```
+
+Alternatively, put `git-delete-merged` somewhere on your `PATH`.
+Git then also accepts it as `git delete-merged`.
 
 ## Usage