Do not test via stack, instead require a successful Linux build.

The latter includes running tests anyway. Also, the testsuite currently
is borked outsite Nix environments. Also also, Stack is garbage and
doesn't support setting up PATH in any sane manner.

.github/workflows/github-actions-image.yaml

@@ -159,7 +159,7 @@ jobs:
           tag: ${{ github.ref }}
 
   dist:
-    needs: check_versions
+    needs: check_versions Linux
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
@@ -189,7 +189,7 @@ jobs:
 
       - name: Build dist
         run: |
-          stack --nix sdist --pvp-bounds both --test-tarball
+          stack --nix sdist --pvp-bounds both
           echo "distPath=$(stack path | awk -F ": " '/dist-dir/ {print $2}')" >> $GITHUB_ENV
 
       - name: Upload compaREST sources artifact
@@ -213,7 +213,7 @@ jobs:
         env:
           HACKAGE_KEY: ${{ secrets.HACKAGE_KEY }}
         run: |
-          stack upload --pvp-bounds both --test-tarball --candidate .
+          stack upload --pvp-bounds both --candidate .
 
   macOS:
     needs: check_versions