Ignore cabal.project.local file

It is produced by Cabal (the tool). See: https://cabal.readthedocs.io/en/stable/cabal-commands.html#cabal-configure

Author: mpilgrem

.gitignore

@@ -23,6 +23,9 @@ hie.yaml
 .hie
 stan.html
 
+# Cabal (the tool)-related
+cabal.project.local
+
 # Emacs-related
 .dir-locals.el
 *_flymake.hs