get the coverage comment info also on master

Author: MaximilianAlgehed

.github/workflows/haskell-ci.yml

@@ -34,9 +34,9 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - run: echo ${{ matrix.ref }}
-
       - uses: actions/checkout@v4
+        with:
+          ref: ${{ matrix.ref }}
 
       - uses: haskell-actions/setup@v2
         with:
@@ -62,6 +62,11 @@ jobs:
       - run: cabal test all
       - run: cabal haddock all
 
+      - uses: actions/checkout@v4
+        with:
+          ref: ${{ github.head_ref }}
+          sparse-checkout:
+            scripts/generate-coverage-comment.sh
 
       - if: ${{ github.event.pull_request }}
         run: ./scripts/generate-coverage-comment.sh constrained.tix | tee coverage-report.md