And support for Gitea workflow

Adds a workflow that will build and test whenever any changes are pushed
to the main branch, or a PR is opened against the main branch.

.gitea/workflows/build-and-test.yaml

@@ -0,0 +1,33 @@
+name: "BuildTest"
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    breanches: [ main ]
+
+jobs:
+  build:
+    name: "Build and test"
+    runs-on: ubuntu-latest
+    steps:
+      - name: "Install build deps"
+        run: |
+          export DEBIAN_FRONTEND=noninteractive
+          sudo apt-get update
+          sudo apt-get -y --no-install-recommends install build-essential \
+            texlive-latex-base texlive-latex-recommended
+
+      - name: "Checkout repo"
+        uses: actions/checkout@v3
+
+      - name: "Bootstrap nuweb"
+        run: make nuweb
+
+      - name: "Make nuweb.tex"
+        run: make nuweb.tex nuwebdoc.tex
+
+      - name: "Build again"
+        run: make nuweb
+
+      - name: "Run tests"
+        run: make check