update CI workflow to include artifact archiving step

.gitea/workflows/ci.yml

@@ -6,5 +6,12 @@ jobs:
       runs-on: ubuntu-latest
       steps:
         - uses: actions/checkout@v4
+        
         - name: build using gcc
           run: gcc -wall -werror main.c
+        
+        - name: Archive production artifacts
+          uses: actions/upload-artifact@v3
+          with:
+            name: program
+            path: program