GitHub CI: Nixpkgs_unstable_macOS: upd

M  .github/workflows/main.yml

Author: Anton-Latukha

.github/workflows/main.yml

@@ -121,10 +121,12 @@ jobs:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Determined nix-build
       run: ./build.sh
-  Nixpkgs_default_macOS:
-    name: Nixpkgs, default (GHC 8.8), macOS
+  Nixpkgs_unstable_macOS:
+    name: Nixpkgs, unstable, default (GHC 8.8), macOS
     runs-on: macos-latest
     continue-on-error: true
+    env:
+      rev: "nixpkgs-unstable"
     steps:
     - name: Git checkout
       uses: actions/checkout@v2