Adding Vala nightly CI

.github/workflows/build-nightly.yml

@@ -0,0 +1,28 @@
+name: CI (vala nightly)
+
+on: [push]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@master # check out code
+    - run: sudo apt-get update
+    - run: sudo apt-get install python3-setuptools valac libvala-dev libgee-0.8-dev libjsonrpc-glib-1.0-dev ninja-build
+    - run: sudo pip3 install meson
+    - run: git clone https://gitlab.gnome.org/Prince781/vala
+    - run: pushd vala
+    - run: git --version
+    - run: git checkout -b lsp --track 9818341931d9182f8514ce671efc8ba8becae4d3
+    - run: ./autogen.sh
+    - run: make -j`nproc`
+    - run: sudo make install
+    - run: popd
+    - run: env PKG_CONFIG_PATH="/usr/local/lib/pkgconfig:/usr/lib/pkgconfig" meson build
+    - run: ninja -C build
+    - uses: elementary/actions/vala-lint@master
+      with:
+        conf: .vala-lint.conf
+        fail: false