ci: flakes on latest ubuntu

Signed-off-by: Christina Sørensen <ces@fem.gg>

.github/workflows/unit-tests.yml

@@ -63,7 +63,7 @@ jobs:
   flake-check:
     needs: conventional
     name: Check Nix Flake
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-latest
     strategy:
       matrix:
         checks: [build, formatting, lint, pre-commit-check, test, trycmd]
@@ -75,7 +75,7 @@ jobs:
       - name: Setup Nix cache
         uses: DeterminateSystems/magic-nix-cache-action@main
       - name: Nix Flake Check
-        run: nix build .#packages.${{ matrix.target }}.${{ matrix.checks }} -L
+        run: nix build .#checks.${{ matrix.target }}.${{ matrix.checks }} -L
 
   flake-build:
     needs: conventional
@@ -84,7 +84,7 @@ jobs:
     strategy:
       matrix:
         target: [x86_64-linux]
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
       - name: Install Nix