ci: Bump the oldest xmonad version we test against

liskin · liskin · commit 984aedc88e13 · 2024-05-13T12:10:30.000+01:00
Stackage LTS 22 has mtl-2.3 and unix-2.8, which xmonad 0.17 excludes in
its bounds.
diff --git a/stack.yaml b/stack.yaml
@@ -8,7 +8,7 @@ packages:
 
 extra-deps:
 - X11-1.10.2
-- xmonad-0.17.0
+- xmonad-0.18.0
 
 nix:
   packages:
diff --git a/xmonad-contrib.cabal b/xmonad-contrib.cabal
@@ -65,7 +65,7 @@ library
                    mtl >= 1 && < 3,
                    unix,
                    X11 >= 1.10 && < 1.11,
-                   xmonad >= 0.16.99999 && < 0.19,
+                   xmonad >= 0.18.0 && < 0.19,
                    utf8-string,
                    deepseq
     default-language: Haskell2010
