ci: add a workflow for release

.github/workflows/release.yml

@@ -0,0 +1,30 @@
+name: Release
+on:
+  push:
+    tags:
+      - "*"
+jobs:
+  github:
+    name: GitHub
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@v4
+      - name: Extract release note
+        run: |
+          ruby \
+            -e 'print("## grntest "); \
+                puts(ARGF.read.split(/^## /)[1]. \
+                       gsub(/ {.+?}/, ""). \
+                       gsub(/\[(.+?)\]\[.+?\]/) {$1})' \
+            doc/text/news.md > release-note.md
+      - name: Upload to release
+        run: |
+          title=$(head -n1 release-note.md | sed -e 's/^## //')
+          tail -n +2 release-note.md > release-note-without-version.md
+          gh release create ${GITHUB_REF_NAME} \
+            --discussion-category Announcements \
+            --notes-file release-note-without-version.md \
+            --title "${title}"
+        env:
+          GH_TOKEN: ${{ github.token }}