Use GitHub Actions as CI to test whether the LaTeX source builds.

.github/workflows/ci.yml

@@ -0,0 +1,12 @@
+name: Build LaTeX document
+on: [push]
+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@master
+        with:
+          root_file: thesis.tex