Tentative fix for previous CI failure.

Author: guibou

flake.nix

@@ -351,7 +351,7 @@
           haskell-language-server-8107 = mkExe ghc8107;
           haskell-language-server-901 = mkExe ghc901;
           haskell-language-server-921 = mkExe ghc921;
-        };
+        } // devShells;
 
         devShells = simpleDevShells // nixDevShells;