.gitea/workflows: add workflow for building database

.gitea/workflows/build.yml

@@ -0,0 +1,28 @@
+name: "Build database"
+on:
+  pull_request:
+  push:
+jobs:
+  evals:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+
+    - name: Install sudo
+      run: apt-get update && apt-get -y install sudo
+
+    - name: Install nix
+      uses: https://github.com/cachix/install-nix-action@v31
+
+    - name: Configure nix
+      run: echo -e "show-trace = true\nmax-jobs = auto\ntrusted-users = root\nexperimental-features = nix-command flakes\nbuild-users-group =" > /etc/nix/nix.conf
+
+    - name: Update database inputs
+      run: |
+        nix flake update jmdict-src
+        nix flake update jmdict-with-examples-src
+        nix flake update radkfile-src
+        nix flake update kanjidic2-src
+
+    - name: Build database
+      run: nix build .#database -L