fix(dap): don't mess up DAP adapters provided by nvim-dap-python

* mason-nvim-dap.nvim ships a `Python: Launch file` adapter which does
  the same thing as `Launch file` of nvim-dap-python, providing both
  doesn't make sense and confuses the users.
* mason-nvim-dap.nvim unexpectedly overrides nvim-dap-python's adapters
  and breaks its venv detection. As a result, user programs are always
  executed in mason debugpy venv rather than the activated one.

Fixes #3064

lua/lazyvim/plugins/extras/lang/python.lua

@@ -138,4 +138,15 @@ return {
       table.insert(opts.auto_brackets, "python")
     end,
   },
+
+  -- Don't mess up DAP adapters provided by nvim-dap-python
+  {
+    "jay-babu/mason-nvim-dap.nvim",
+    optional = true,
+    opts = {
+      handlers = {
+        python = function() end,
+      },
+    },
+  },
 }