Declare tasty-discover a testing build tool (#130)

This properly fixes the use of the tasty-discover,
the report & info were sent upstream to fix it in docs:
https://github.com/haskell-works/tasty-discover/issues/4.
Closes: #129

.github/workflows/Cabal-Linux.yml

@@ -40,7 +40,7 @@ jobs:
         run: cabal v2-update
 
       - name: "Install additional system packages"
-        run: sudo apt install libsodium-dev && cabal v2-install tasty-discover
+        run: sudo apt install libsodium-dev
 
       # Still required for Remote
       - name: "Install Nix"

.github/workflows/On-Release-Cabal-Linux.yml

@@ -39,7 +39,7 @@ jobs:
         run: cabal v2-update
 
       - name: "Install additional system packages"
-        run: sudo apt install libsodium-dev && cabal v2-install tasty-discover
+        run: sudo apt install libsodium-dev
 
       # Still required for Remote
       - name: "Install Nix"

hnix-store-core/hnix-store-core.cabal

@@ -90,6 +90,8 @@ test-suite format-tests
       StorePath
   hs-source-dirs:
       tests
+  build-tool-depends:
+    tasty-discover:tasty-discover
   build-depends:
       hnix-store-core
     , attoparsec

hnix-store-remote/hnix-store-remote.cabal

@@ -67,6 +67,8 @@ test-suite hnix-store-remote-tests
                    , Spec
                    , Util
   hs-source-dirs:    tests
+  build-tool-depends:
+    tasty-discover:tasty-discover
   build-depends:     base
                    , hnix-store-core >= 0.3
                    , hnix-store-remote

overlay.nix

@@ -1,17 +1,11 @@
 pkgs: hlib: helf: huper: {
   hnix-store-core =
-    ( helf.callCabal2nix "hnix-store-core" ./hnix-store-core {}
-    ).overrideAttrs (attrs: {
-        buildInputs = attrs.buildInputs ++ [
-          pkgs.haskellPackages.tasty-discover
-        ];
-    });
+    helf.callCabal2nix "hnix-store-core" ./hnix-store-core {};
   hnix-store-remote =
     ( helf.callCabal2nixWithOptions "hnix-store-remote" ./hnix-store-remote "-fio-testsuite" {}
     ).overrideAttrs (attrs: {
         buildInputs = attrs.buildInputs ++ [
           pkgs.nix
-          pkgs.haskellPackages.tasty-discover
         ];
     });
 }