*/ci: Have tests use nix flake

Signed-off-by: Naomi Roberts <[e-mail]>

.tangled/workflows/test.yml

···
   depth: 1
   submodules: false
 
-dependencies:
-  github:NixOS/nixpkgs/nixpkgs-unstable:
-    - gleam
-    - beamMinimal28Packages.erlang
-    - beamMinimal28Packages.rebar3
-
 steps:
-  - name: Setup
-    command: |
-      export PATH="$HOME/.nix-profile/bin:$PATH"
-  - name: Test alicia/identity
-    command: |
-      cd alicia/identity
-      gleam test
-      cd -
+  - name: Test all
+    command: nix run .#test

flake.nix

···
           '';
         })}/bin/run-lexgen";
       };
+      test = {
+        type = "app";
+        program = "${(pkgs.writeShellApplication {
+          inherit runtimeInputs;
+          name = "run-tests";
+          text = ''
+            ${cdInto "alicia/identity"}
+            ${pkgs.gleam}/bin/gleam test
+            ${cdInto ""}
+          '';
+        })}/bin/run-tests";
+      };
     });
   };
 }