Automatically create and upload release artifacts (#30)

When a new release is created, this will build the release artifacts and upload them to the release and ensures that the description text matches the one in the default template in HELICS's release checklist.

An extra layer of nested archives is also removed -- so release will no longer will have a tar.gz or zip files inside the artifact zip file that was uploaded to previous releases.

Fixes #20

.github/workflows/ci.yml

@@ -1,13 +1,15 @@
 name: Test matHELICS
-
 on:
   push:
+    branches:
+      - main
   pull_request:
     branches:
       - main
+  release:
+    types:
+      - published
   workflow_dispatch:
-  #schedule:
-  #  - cron: "35 10 * * 1,3,5 # running early in the morning (UTC)
 
 jobs:
   ci-test:
@@ -39,11 +41,17 @@ jobs:
         uses: matlab-actions/run-command@v2
         with:
           command: buildHelicsInterface('helics',true)
+      - name: Rename artifact (Windows)
+        if: runner.os == 'Windows'
+        run: mv matHELICS.zip matHELICS-${{ matrix.os }}.zip
+      - name: Rename artifact
+        if: runner.os != 'Windows'       
+        run: mv matHELICS.tar.gz matHELICS-${{ matrix.os }}.tar.gz
       - name: store package
         uses: actions/upload-artifact@v4
         with:
           name: ${{ matrix.os }}-matHELICS
-          path: matHELICS.*
+          path: matHELICS-${{ matrix.os }}.*
       - name: run startup
         uses: matlab-actions/run-command@v2
         with:
@@ -53,3 +61,20 @@ jobs:
         with:
           command: addpath('tests'),addpath('helics'),runAllTests
 
+  release:
+    if: github.event_name == 'release' && github.event.action == 'published'
+    runs-on: ubuntu-latest
+    needs: ci-test
+    steps:
+      - name: Download artifact
+        uses: actions/download-artifact@v4
+        with: # no name specified, so all artifacts will be downloaded
+          path: ./artifacts
+          merge-multiple: true
+      - name: List files in artifacts
+        run: ls ./artifacts
+      - name: Create Release
+        uses: softprops/action-gh-release@v2
+        with:
+          body: Release for [HELICS ${{ github.ref_name }}](https://github.com/GMLC-TDC/HELICS/releases/tag/${{ github.ref_name }})
+          files: ./artifacts/matHELICS-*