Remove nixpkgs 21.11 from CI and reduce tests

The time taken to run CI is getting very long.  Hopefully removing nixpkgs 21.11 and no longer runs full tests for GHC 9.0.2 well make room for GHC 9.4.1.

Author: hamishmack

ci.nix

@@ -10,7 +10,6 @@
   inherit (import ./ci-lib.nix { inherit pkgs; }) dimension platformFilterGeneric filterAttrsOnlyRecursive;
   inherit (pkgs.haskell-nix) sources;
   nixpkgsVersions = {
-    "R2111" = "nixpkgs-2111";
     "R2205" = "nixpkgs-2205";
     "unstable" = "nixpkgs-unstable";
   };
@@ -30,17 +29,14 @@
     # cabal-install and nix-tools plans.  When removing a ghc version
     # from here (so that is no longer cached) also remove ./materialized/ghcXXX.
     # Update supported-ghc-versions.md to reflect any changes made here.
-    nixpkgs.lib.optionalAttrs (nixpkgsName == "R2111") {
+    nixpkgs.lib.optionalAttrs (nixpkgsName == "R2205") {
       ghc865 = false;
-      ghc8107 = true;
-    } // nixpkgs.lib.optionalAttrs (nixpkgsName == "R2205") {
-      ghc865 = false;
-      ghc8107 = true;
+      ghc8107 = false;
     } // nixpkgs.lib.optionalAttrs (nixpkgsName == "unstable") {
       ghc865 = false;
       ghc884 = false; # Native version is used to boot 9.0.1
       ghc8107 = true;
-      ghc902 = true;
+      ghc902 = false;
       ghc924 = true;
     });
   systems = nixpkgsName: nixpkgs: compiler-nix-name: nixpkgs.lib.genAttrs (

docs/reference/supported-ghc-versions.md

@@ -21,12 +21,12 @@ really should use an instance of Nixpkgs provided by `haskell.nix` itself.
 
 | Nixpkgs version  | Nixpkgs pinning    | GHC version | `compiler-nix-name`   | Tested in CI? |
 |------------------|--------------------|-------------|-----------------------|---------------|
-| 21.11            | `nixpkgs-2111`     | 8.6.5       | `ghc865`              | No            |
-| 21.11            | `nixpkgs-2111`     | 8.10.7      | `ghc8107`             | Yes           |
+| 22.05            | `nixpkgs-2205`     | 8.6.5       | `ghc865`              | No            |
+| 22.05            | `nixpkgs-2205`     | 8.10.7      | `ghc8107`             | No            |
 | unstable         | `nixpkgs-unstable` | 8.6.5       | `ghc865`              | No            |
 | unstable         | `nixpkgs-unstable` | 8.8.4       | `ghc884`              | No            |
 | unstable         | `nixpkgs-unstable` | 8.10.7      | `ghc8107`             | Yes           |
-| unstable         | `nixpkgs-unstable` | 9.0.2       | `ghc902`              | Yes           |
+| unstable         | `nixpkgs-unstable` | 9.0.2       | `ghc902`              | No            |
 | unstable         | `nixpkgs-unstable` | 9.2.4       | `ghc924`              | Yes           |
 
 See [ci.nix](https://github.com/input-output-hk/haskell.nix/blob/master/ci.nix)