CI: GitHub: Nix: dontCheck (#807)

The Cabal testing is really enough.

Maybe form a network test switch and disable those tests when the variable is
set. So we configure that in the CI and in Nixpkgs.

Author: Anton-Latukha

.github/workflows/Optional-Nix-dev-env-macOS.yml

@@ -16,6 +16,7 @@ env:
   # rev: "nixos-unstable"         #  2020-09-29: NOTE: HNix default.nix currently pins the rev
   cachixAccount: "hnix"
   CACHIX_SIGNING_KEY: ${{ secrets.CACHIX_SIGNING_KEY }}
+  doCheck: "false"
 
 
 jobs:

.github/workflows/Optional-Nix-dev-env-main.yml

@@ -27,7 +27,7 @@ env:
   CACHIX_SIGNING_KEY: ${{ secrets.CACHIX_SIGNING_KEY }}
   allowInconsistentDependencies: "false"
   doJailbreak: "false"
-  doCheck: "true"
+  doCheck: "false"
   sdistTarball: "false"
   buildFromSdist: "false"
   buildStrictly: "false"