ci: github action to notify releases via irc

.github/workflows/release_notify.yml

@@ -0,0 +1,20 @@
+name: Release notifier
+
+on:
+  release:
+    types: [published]
+
+jobs:
+  notify:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Notify IRC
+        uses: Gottox/irc-message-action@v2
+        with:
+          server: "irc.libera.chat"
+          channel: "#shiori"
+          nickname: ShioriBot
+          tls: true
+          sasl_password: ${{ secrets.IRC_SHIORIBOT_PWD }}
+          message: "New release: ${{ github.event.repository.full_name }}@${{ github.event.release.name }}: ${{ github.event.release.html_url }}"