ci: add workflow for compilation and release

Add a simple workflow config that gets triggered based on tags start
with `v*`. This workflow compiles the LaTeX document with the
root file `main.tex` that generates `main.pdf` according to the default
behavior provided in [latex-action]. Then, the release action takes
place according to the behavior provided in [action-gh-release]

[latex-action]: https://github.com/xu-cheng/latex-action
[action-gh-release]: https://github.com/softprops/action-gh-release

.github/workflows/release.yml

@@ -0,0 +1,21 @@
+name: Build LaTeX document
+
+on:
+  push:
+    tags:
+      - "v*"
+jobs:
+  build_latex:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Set up Git repository
+        uses: actions/checkout@v2
+      - name: Compile LaTeX document
+        uses: xu-cheng/latex-action@v2
+        with:
+          root_file: main.tex
+      - name: Release
+        uses: softprops/action-gh-release@v1
+        with:
+          generate_release_notes: true
+          files: main.pdf