add upload-artifact

.gitea/workflows/ci.yml

@@ -7,4 +7,9 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - name: build using gcc
-        run: gcc -Wall -Werror main.c
+        run: gcc -Wall -Werror main.c -o program
+      - name: Archive production artifacts
+        uses: actions/upload-artifact@v3
+        with:
+          name: program
+          path: program