[ci] Add at least some caching

.forgejo/workflows/test-bootstrap.yaml

@@ -19,6 +19,21 @@ jobs:
           cp "$(pwd)/bootstrap/chezmoi.toml" "${HOME}/.config/chezmoi"
       - run: |
           chezmoi apply
+      - name: Restore cached Doom
+        id: cache-doom-restore
+        uses: actions/cache/restore@v4
+        with:
+          path: |
+            .emacs.d
+          key: ${{ runner.os }}-doom
+      - run: |
+          git clone --depth 1 https://github.com/doomemacs/doomemacs ~/.emacs.d || (cd ~/.emacs.d && git pull)
+      - name: Save Primes
+        id: cache-doom-save
+        uses: actions/cache/save@v4
+        with:
+          path: |
+            .emacs.d
+          key: ${{ steps.cache-doom-restore.outputs.cache-primary-key }}
       - run: |
-          git clone --depth 1 https://github.com/doomemacs/doomemacs ~/.emacs.d
           ~/.emacs.d/bin/doom sync