Add cabal.project

Add `.vscode` to `.gitignore`

.github/workflows/ci.yaml

@@ -33,9 +33,6 @@ jobs:
         key: ${{ runner.os }}-${{ matrix.ghc }}
     - name: Build
       run: |
-        echo packages:. > cabal.project
-        echo tests:True >> cabal.project
-        echo "constraints:quickcheck-classes -semigroupoids -aeson -semirings" >> cabal.project
         cabal test --test-show-details=direct
         cabal bench --benchmark-option=-l
         cabal sdist
@@ -176,9 +173,6 @@ jobs:
         key: ${{ runner.os }}-latest
     - name: Test
       run: |
-        echo packages:. > cabal.project
-        echo tests:True >> cabal.project
-        echo "constraints:quickcheck-classes -semigroupoids -aeson -semirings" >> cabal.project
         echo "constraints:vector +unsafechecks +internalchecks" >> cabal.project
         # Some tests are filtered out because of
         # https://gitlab.haskell.org/ghc/ghc/-/issues/23132

.gitignore

@@ -27,3 +27,9 @@ dist-newstyle
 
 cabal.sandbox.config
 .cabal-sandbox
+
+########
+# IDEs #
+########
+
+.vscode

cabal.project

@@ -0,0 +1,5 @@
+packages: .
+tests: True
+
+package quickcheck-classes
+    flags: -aeson -semigroupoids -semirings