CI: widen bogus bounds to include cabal v2 [kick 9]

multiple-components-example/multiple-components-example.cabal

@@ -34,8 +34,18 @@ custom-setup
   setup-depends:
       base           < 5
     , cabal-doctest  >=1.0.9 && <1.1
-    -- not used directly in Setup.hs, but fixes `stack build`.
-    , Cabal == 3.*
+
+    -- Declaring this setup-dep fixes `stack build`. NOTE: Cabal API is not used directly
+    -- in the examples' Setup.hs! Instead, indirectly through wrappings of cabal-doctest.
+    --
+    -- When copying the example, you may of course delete this note, and start importing
+    -- Cabal stuff directly from Setup.hs.
+    --  ! Make sure to set a tighter bound, e.g. Cabal <3.16, here in setup-depends !
+    -- as soon as you do that.
+    , Cabal >= 1.24 && <4
+    -- > Warning: [...] Each major release of the 'Cabal' package changes the API
+    -- > in various ways and most packages will need some changes to compile with it.
+    -- > If you are not sure what upper bound to use then use the next major version.
 
 library
   exposed-modules:    Example

simple-example/simple-example.cabal

@@ -33,8 +33,18 @@ custom-setup
   setup-depends:
       base           < 5
     , cabal-doctest  >=1.0.9 && <1.1
-    -- not used directly in Setup.hs, but fixes `stack build`.
-    , Cabal == 3.*
+
+    -- Declaring this setup-dep fixes `stack build`. NOTE: Cabal API is not used directly
+    -- in the examples' Setup.hs! Instead, indirectly through wrappings of cabal-doctest.
+    --
+    -- When copying the example, you may of course delete this note, and start importing
+    -- Cabal stuff directly from Setup.hs.
+    --  ! Make sure to set a tighter bound, e.g. Cabal <3.16, here in setup-depends !
+    -- as soon as you do that.
+    , Cabal >= 1.24 && <4
+    -- > Warning: [...] Each major release of the 'Cabal' package changes the API
+    -- > in various ways and most packages will need some changes to compile with it.
+    -- > If you are not sure what upper bound to use then use the next major version.
 
 library
   exposed-modules:    Example