workflow: add release pipeline

- Minor change in push pipeline to remove spaces from artifact name
- Create release pipeline with the same steps that will upload a zipped
  package to every published release automatically

.github/workflows/release.yml

@@ -0,0 +1,39 @@
+name: Build Pico Launcher release
+
+on:
+  release:
+    types: [published]
+
+jobs:
+  pico_launcher:
+    runs-on: ubuntu-latest
+    container: skylyrac/blocksds:slim-v1.13.1
+    name: Build Pico Launcher
+    steps:
+      - name: Checkout repo
+        uses: actions/checkout@v4
+        with:
+          submodules: true
+      - name: Install zip
+        run:
+          apt-get update && apt-get -y install zip
+      - name: Run build script
+        run: |
+          make
+      - name: Publish build to GH Actions
+        uses: actions/upload-artifact@v4
+        with:
+          path: |
+            _pico/
+            LAUNCHER.nds
+          name: Pico_Launcher
+      - name: Package for release
+        run: |
+          mkdir Pico_Launcher
+          cp -r _pico/ LAUNCHER.nds Pico_Launcher
+          cd Pico_Launcher && zip -r $PWD.zip *
+      - name: Release
+        uses: softprops/action-gh-release@v2
+        with:
+          files: |
+            Pico_Launcher.zip