[INFRA] Simplify release announces (#174)

Add a new workflow to send message on twitter & discord, after a new
release is published.

Author: csouchet

.github/workflows/announce-new-release.yml

@@ -0,0 +1,46 @@
+name: Announce new release
+on:
+  workflow_dispatch:
+    inputs:
+      version:
+        description: 'The version to announce'
+        type: string
+        required: true
+      description:
+        description: 'A short description of the version to announce'
+        type: string
+        required: true
+
+jobs:
+  publish_tweet:
+    runs-on: ubuntu-22.04
+    steps:
+      - name: Publish a tweet
+        uses: snow-actions/tweet@v1.4.0
+        with:
+          status: |
+            📣 bpmnVisualizationR ${{ github.event.inputs.version }} is out! 🎉
+
+            ${{ github.event.inputs.description }}
+
+            #bpmnvisualization #bpmn #visualization #R #RLang #programming #opensource
+            ${{ github.server_url }}/${{ github.repository }}/releases/tag/v${{ github.event.inputs.version }}
+        env:
+          CONSUMER_API_KEY: ${{ secrets.TWITTER_CONSUMER_API_KEY }}
+          CONSUMER_API_SECRET_KEY: ${{ secrets.TWITTER_CONSUMER_API_SECRET_KEY }}
+          ACCESS_TOKEN: ${{ secrets.TWITTER_ACCESS_TOKEN }}
+          ACCESS_TOKEN_SECRET: ${{ secrets.TWITTER_ACCESS_TOKEN_SECRET }}
+
+  publish_discord_post:
+    runs-on: ubuntu-22.04
+    steps:
+      - name: Publish a message on Discord
+        uses: sarisia/actions-status-discord@v1
+        with:
+          webhook: ${{ secrets.DISCORD_WEBHOOK }}
+          nodetail: true
+          notimestamp: true
+          title: 📣 `bpmnVisualizationR` ${{ github.event.inputs.version }} is out! 🎉
+          url: ${{ github.server_url }}/${{ github.repository }}/releases/tag/v${{ github.event.inputs.version }}
+          description: ${{ github.event.inputs.description }}
+          color: 0xF9DADC

MAINTAINERS.md

@@ -119,8 +119,15 @@ It conforms to [the CRAN Submission policies first](https://cran.r-project.org/w
 
 ## Communicate about the release
 
-**NOTE**: this is a very manual process today. For improvements, see [#130](https://github.com/process-analytics/bpmn-visualization-R/issues/130)
+- Open [github actions](https://github.com/process-analytics/bpmn-visualization-R/actions/workflows/announce-new-release.yml)
+- Click on the 'Run workflow' dropdown located on the right side of the page
+- Provide parameter values for _version_ and _description_
+- Click on the button 'Run workflow'
+- Make sure job execution was successful by checking the status
+- If all is good, you should see a new tweet on [ProcessAnalyti1](https://twitter.com/ProcessAnalyti1) and a new message on the [news](https://discord.com/channels/1011911769607913562/1024329159033499780) channel of Process Analytics server on Discord.
 
+___
+⚠️⚠️⚠️ _**Only if the [jobs](https://github.com/process-analytics/bpmn-visualization-R/actions/workflows/announce-new-release.yml) does NOT work!**_  ⚠️⚠️⚠️
 ### Twitter
 
 You can use this template:
@@ -144,3 +151,6 @@ You can use this template:
 > ===> some short description here <===
 >
 > https://github.com/process-analytics/bpmn-visualization-R/releases/tag/v{version}
+
+⚠️⚠️⚠️ _**End of the manual steps**_ ⚠️⚠️⚠️
+___