chore: update Nix workflow to not return error (#683)

The script is expected to fail, so we need to handle that value. This
commit changes Nix script to not fail anymore (it will always succeed)
and it will update `nix/hash` to new value as needed.

Additionally this updates value immediately.

Author: hauleth

.github/workflows/nix.yml

@@ -16,7 +16,7 @@ jobs:
       - uses: DeterminateSystems/nix-installer-action@main
       - uses: DeterminateSystems/magic-nix-cache-action@main
       - run: |
-          nix run .#update-hash
+          nix run .#update-hash | tee nix/hash
           git config user.email ""
           git config user.name "GitHub Action Bot"
           git commit -m 'Update Nix hash of Mix deps' nix/hash && git push || true

flake.nix

@@ -38,7 +38,7 @@
 
             text = ''
               nix --extra-experimental-features 'nix-command flakes' \
-                build --no-link "${self}#__fodHashGen" 2>&1 | gawk '/got:/ { print $2 }'
+                build --no-link "${self}#__fodHashGen" 2>&1 | gawk '/got:/ { print $2 }' || true
             '';
           };
         in {

nix/hash

@@ -1 +1 @@
-sha256-G0mT+rvXZWLJIMfrhxq3TXt26wDImayu44wGEYJ+3CE=
+sha256-TnWGHD1Is7rX/zS1+3+9B+dWsGXX2sm/abF1cnFkEeA=