Remove Stack from CI altogether

.github/workflows/haskell.yml

@@ -47,36 +47,3 @@ jobs:
     - name: Test
       run: |
         cabal test all --enable-tests --test-show-details=streaming
-
-  stack:
-    name: ${{ matrix.os }} stack / ghc ${{ matrix.ghc }}
-    runs-on: ${{ matrix.os }}
-    strategy:
-      matrix:
-        os: [ubuntu-latest, windows-latest]
-        stack: ["latest"]
-        ghc: ["8.8.3"]
-
-    steps:
-    - uses: actions/checkout@v2
-      if: github.event.action == 'opened' || github.event.action == 'synchronize' || github.event.ref == 'refs/heads/master'
-
-    - uses: actions/[email protected]
-      name: Setup Haskell Stack
-      with:
-        ghc-version: ${{ matrix.ghc }}
-        stack-version: ${{ matrix.stack }}
-
-    - uses: actions/cache@v1
-      name: Cache ~/.stack
-      with:
-        path: ~/.stack
-        key: ${{ runner.os }}-${{ matrix.ghc }}-stack
-
-    - name: Build
-      run: |
-        stack build --system-ghc --test --no-run-tests
-
-    - name: Test
-      run: |
-        stack test --system-ghc

TODO.md

@@ -26,6 +26,5 @@ anyone, they should become issues or PRs, and be removed from this list.
   elucidated or specified - this should happen.
 * Figure out why our CI settings break on the following combinations:
   * Cabal latest, Windows latest, GHC 8.8.3
-  * Stack latest, macOS latest, GHC 8.6.5
 * Checking custom schemata currently relies on an unsafe construction. This
   should be replaced by a safer one.