Don't use nightly to build docs

Author: alt-romes

.github/workflows/release.yaml

@@ -27,9 +27,9 @@ jobs:
 
       - uses: haskell-actions/setup@v2
         with:
-          ghc-version: latest-nightly
+          ghc-version: 9.14.0.20250819
           cabal-version: 3.14
-          ghcup-release-channel: https://ghc.gitlab.haskell.org/ghcup-metadata/ghcup-nightlies-0.0.7.yaml
+          ghcup-release-channel: https://raw.githubusercontent.com/haskell/ghcup-metadata/refs/heads/develop/ghcup-prereleases-0.0.9.yaml
 
       - name: Build docs for haskell-debugger
         run: cabal haddock --haddock-for-hackage --enable-documentation