feat(gleam): add conform (#5640)

## Description

Add conform.nvim formatter for gleam lanuage.

## Checklist

- [x] I've read the
[CONTRIBUTING](https://github.com/LazyVim/LazyVim/blob/main/CONTRIBUTING.md)
guidelines.

lua/lazyvim/plugins/extras/lang/gleam.lua

@@ -17,4 +17,13 @@ return {
       },
     },
   },
+  {
+    "conform.nvim",
+    optional = true,
+    opts = {
+      formatters_by_ft = {
+        gleam = { "gleam" },
+      },
+    },
+  },
 }