Bump haskell-actions/setup to get 9.6.4 in CI (#4062)

Author: jhrcek

.github/actions/setup-build/action.yml

@@ -31,7 +31,7 @@ runs:
         sudo chown -R $USER /usr/local/.ghcup
       shell: bash
 
-    - uses: haskell-actions/setup@v2.6.0
+    - uses: haskell-actions/setup@v2.6.1
       id: HaskEnvSetup
       with:
         ghc-version  : ${{ inputs.ghc   }}