Add a release actions

Github workflows to create a nightly release automatically and a
stable release semi-automatic (a 2-step process).

.github/workflows/release.yml

@@ -0,0 +1,43 @@
+name: Release
+on:
+  push:
+    tags:
+      - 'v*'
+jobs:
+  release:
+    runs-on: ubuntu-20.04
+    strategy:
+      fail-fast: true
+      matrix:
+        java: [ 'openjdk@1.11' ]
+    steps:
+      - uses: actions/checkout@v2.3.4
+        with:
+          fetch-depth: 0
+      - uses: olafurpg/setup-scala@v10
+        with:
+          java-version: ${{ matrix.java }}
+      - uses: jorelali/setup-elm@v3
+        with:
+          elm-version: 0.19.1
+      - uses: bahmutov/npm-install@v1
+      - name: Coursier cache
+        uses: coursier/cache-action@v6
+      - name: Set current version
+        run:  echo "DOCSPELL_VERSION=$(cat version.sbt | grep version | cut -d= -f2 | xargs)" >> $GITHUB_ENV
+      - name: sbt make-pkg (${{ env.DOCSPELL_VERSION }})
+        run: sbt make-pkg
+      - uses: meeDamian/github-release@2.0
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          name: Docspell ${{ env.DOCSPELL_VERSION }}
+          gzip: false
+          draft: true
+          prerelease: false
+          allow_override: false
+          files: >
+            modules/restserver/target/docspell-restserver_${{ env.DOCSPELL_VERSION }}_all.deb
+            modules/restserver/target/universal/docspell-restserver-${{ env.DOCSPELL_VERSION }}.zip
+            modules/joex/target/docspell-joex_${{ env.DOCSPELL_VERSION }}_all.deb
+            modules/joex/target/universal/docspell-joex-${{ env.DOCSPELL_VERSION }}.zip
+            tools/target/docspell-tools-${{ env.DOCSPELL_VERSION }}.zip