update ci and install gopls

.github/workflows/ci.yml

@@ -8,6 +8,9 @@ jobs:
     runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2
+      - uses: actions/setup-go@v2
+        with:
+          go-version: '^1.15.1' # The Go version to download (if necessary) and use.
       - run: date +%F > todays-date
       - name: Restore cache for today's nightly.
         uses: actions/cache@v2
@@ -25,12 +28,16 @@ jobs:
             chmod +x nvim.appimage
             mv nvim.appimage ./build/nvim
           }
+          GO111MODULE=on go get golang.org/x/tools/gopls@latest
+
           mkdir -p ~/.local/share/nvim/site/pack/vendor/start
           git clone --depth 1 https://github.com/nvim-lua/plenary.nvim ~/.local/share/nvim/site/pack/vendor/start/plenary.nvim
           git clone --depth 1 https://github.com/ray-x/guihua.lua ~/.local/share/nvim/site/pack/vendor/start/guihua.lua
+          git clone --depth 1 https://github.com/nvim-treesitter/nvim-treesitter ~/.local/share/nvim/site/pack/vendor/start/nvim-treesitter
           git clone --depth 1 https://github.com/kyazdani42/nvim-web-devicons ~/.local/share/nvim/site/pack/vendor/start/nvim-web-devicons
           ln -s $(pwd) ~/.local/share/nvim/site/pack/vendor/start
       - name: Run tests
         run: |
             export PATH="${PWD}/build/:${PATH}"
+            nvim --headless -u tests/minimal.vim -c "TSInstallSync go" -c "q"
             make test