Add release flow to GitHub Actions

Initial support to automate release flow. Now after git tag of specific commit GitHub Actions will create a draft entry of release (named by tag) with source code package on it.

.github/workflows/release.yml

@@ -0,0 +1,30 @@
+name: Release source tarball
+on:
+  push:
+    tags:
+      - '*'
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          submodules: recursive
+
+      - name: Generate git hash and tarball
+        run: |
+          sudo apt update
+          sudo apt install -y ninja-build cmake g++ libsdl2-dev zlib1g-dev
+          cmake --preset linux
+          cmake --build --preset linux -t get_git_hash
+          cmake --build --preset linux -t package_source
+
+      - name: Release
+        uses: ncipollo/[email protected]
+        with:
+          artifacts: "builds/linux/Descent3-*-Source.tar.xz"
+          draft: true
+          token: ${{ secrets.GITHUB_TOKEN }}

CMakeLists.txt

@@ -253,3 +253,17 @@ add_subdirectory(tools)
 add_subdirectory(netcon)
 add_subdirectory(netgames)
 add_subdirectory(scripts)
+
+# Packaging stuff
+set(CPACK_SOURCE_GENERATOR "TXZ")
+set(CPACK_SOURCE_IGNORE_FILES
+  ".git/"
+  ".github/"
+  ".idea"
+  build[s]/
+  cmake-build-*
+  ".*~$"
+)
+set(CPACK_VERBATIM_VARIABLES YES)
+include(CPack)
+