use caches to speed up compilation

.gitea/workflows/build.yaml

@@ -33,22 +33,48 @@ jobs:
           .ci/deploy_to_build_repo.sh
         env:
           REF_NAME: ${{ github.ref_name }}
-      - name: Compile documentation
+      - name: Clean up git files from build repo
         if: github.ref == 'refs/heads/master'
-        run: |
+        run: rm -rf build/packages/.git
-          echo ${TEXINPUTS}
+      - name: Save built packages to cache
-          make doc
+        if: github.ref == 'refs/heads/master'
+        uses: actions/cache/save@v3
+        with:
+          path: build/packages/
+          key: ${{ github.ref }}-packages
+
+  pages:
+    runs-on: latex-latest
+    if: github.ref == 'refs/heads/master'
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+      - name: Load package cache
+        uses: actions/cache/restore@v3
+        with:
+          path: build/packages/
+          key: ${{ github.ref }}-packages
+      - name: Load compilation cache
+        uses: actions/cache/restore@v3
+        with:
+          path: .compile
+          key: ${{ github.ref }}-doc
+      - name: Compile documentation
+        run: make doc
         env:
           TEXINPUTS: '${{ github.workspace }}/build/packages//:'
       - name: Prepage pages
-        if: github.ref == 'refs/heads/master'
         run: |
           cd build
           rm -rf packages/.git  # Don't deploy the git files
           zip -r latex-packages.zip packages/ -x '*.git*'
           zip -r latex-packages-doc.zip doc/
       - name: Deploy to pages
-        if: github.ref == 'refs/heads/master'
         uses: actions/pages@v1
         with:
           directory: build/
+      - name: Upload compilation cache
+        uses: actions/cache/save@v3
+        with:
+          path: .compile
+          key: ${{ github.ref }}-doc