Revert "Remove GitHub-related stuff"

This reverts commit 5cf2bd1.

Author: sudotac

.github/workflows/vader.yml

@@ -0,0 +1,31 @@
+name: Fugitive GitLab
+on: [push, pull_request]
+jobs:
+  Vader:
+    strategy:
+      matrix:
+        vim:
+          - package: vim
+            bin: vim
+          - package: neovim
+            bin: nvim
+    runs-on: ubuntu-latest
+    steps:
+      - name: Git clone Vader
+        uses: actions/checkout@v2
+        with:
+          repository: junegunn/vader.vim
+          path: vader.vim
+      - name: Git clone Fugitive
+        uses: actions/checkout@v2
+        with:
+          repository: tpope/vim-fugitive
+          path: vim-fugitive
+      - name: Check out repository code
+        uses: actions/checkout@v2
+        with:
+          path: fugitive-gitlab.vim
+      - name: Install packages
+        run: sudo apt-get install -y ${{ matrix.vim.package }} curl
+      - name: Run vader against ${{ matrix.vim.package }}
+        run: ${{ matrix.vim.bin }} -Es -Nu fugitive-gitlab.vim/test/vimrc -c "Vader! fugitive-gitlab.vim/test/*" 2>&1

README.md

@@ -1,5 +1,7 @@
 # fugitive-cgit.vim
 
+[![Fugitive cgit](https://github.com/sudotac/fugitive-cgit.vim/actions/workflows/vader.yml/badge.svg?branch=master)](https://github.com/sudotac/fugitive-cgit.vim/actions/workflows/vader.yml)
+
 [fugitive.vim][] is undoubtedly the best Git wrapper of all time.
 
 This plugin allows you to use it with a cgit instance.