Add support for Deno (#1446)

* testing gh-action

* commit deno code

* bug

* configured name/email of the commit

* deno tag

* gh-action event

* updated readme

* force new release

* force a new commit

* use external repo for deno version

* checkout using a PAT

* try PAT

.github/workflows/deno.yml

@@ -0,0 +1,53 @@
+name: Deno
+
+on:
+  push:
+    tags:
+      - "8.*"
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Setup Deno environment
+        uses: denolib/setup-deno@v2.2.0
+        with:
+          deno-version: v1.x
+
+      - name: Checkout postcss-deno
+        uses: actions/checkout@v2
+        with:
+          repository: postcss/postcss-deno
+          token: ${{ secrets.PAT }}
+
+      - name: Checkout postcss
+        uses: actions/checkout@v2
+        with:
+          ref: master
+          path: postcss
+
+      - name: Convert the code
+        run: |
+          rm -rf deno
+          deno run --unstable --allow-write --allow-read to_deno.js
+          deno fmt deno
+          cp postcss/README.md deno/
+          cp postcss/CHANGELOG.md deno/
+          cp postcss/LICENSE deno/
+
+          deno test --unstable --allow-read deno/test/*
+
+      - name: Get the tag name
+        id: get_version
+        run: echo ::set-output name=VERSION::${GITHUB_REF/refs\/tags\//}
+
+      - name: Commit the changes and create the tag
+        run: |
+          git config user.name deno-conversion
+          git config user.email github-actions@github.com
+          git add deno
+          git commit -m "update code"
+          git push
+          git tag ${{ steps.get_version.outputs.VERSION }}
+          git push --tags

README.md

@@ -369,6 +369,19 @@ prefixer({ display: 'flex' }) //=> { display: ['-webkit-box', '-webkit-flex', '-
 [webpack]:      https://webpack.github.io/
 
 
+### Deno
+
+PostCSS also supports [Deno], the new JavaScript/TypeScript runtime.
+
+```js
+import postcss from "https://deno.land/x/postcss/mod.js";
+import autoprefixer from "https://dev.jspm.io/autoprefixer";
+
+const result = await postcss([autoprefixer]).process(css);
+```
+
+[Deno]: https://deno.land/
+
 ### Runners
 
 * **Grunt**: [`@lodder/grunt-postcss`](https://github.com/C-Lodder/grunt-postcss)