Add ghcup-gen

cabal.project

@@ -0,0 +1,29 @@
+packages: ./ghcup-gen/ghcup-gen.cabal
+
+package ghcup
+    tests: False
+    flags: -tui +no-exe
+
+source-repository-package
+  type: git
+  location: https://gitlab.haskell.org/haskell/ghcup-hs.git
+  tag: v0.1.17.3
+
+constraints: http-io-streams -brotli,
+             any.Cabal ==3.6.2.0,
+             any.aeson >= 2.0.1.0
+
+package libarchive
+  flags: -system-libarchive
+
+package aeson-pretty
+  flags: +lib-only
+
+package cabal-plan
+  flags: -exe
+
+package aeson
+  flags: +ordered-keymap
+
+allow-newer: base, ghc-prim, template-haskell, language-c
+