try installing sudo

.gitea/workflows/check-flake.yaml

@@ -2,12 +2,15 @@ name: Check Flake
 
 on: [push]
 
+env:
+  DEBIAN_FRONTEND: noninteractive
+
 jobs:
   check-flake:
     runs-on: ubuntu-latest
     steps:
       - name: Install sudo
-        run: apt-get update && apt-get upgrade && apt-get -y --no-install-recommends install sudo
+        run: apt-get update && apt-get install sudo
 
       - name: Install Nix
         uses: https://github.com/cachix/install-nix-action@v20