fix(esupports.indent): fix setting indentation of line to -1 not being ignored

indent-expression might return -1 as the indentation of a line to indicate that
neovim should handle the indentation of the line. When manually setting the
indentation of a line with `buffer_set_line_indent` using the indentation
returned by indent-expression however, the -1 indentation caused the indentation
to be set to 0 instead of kept as is

Author: ALVAROPING1

lua/neorg/modules/core/esupports/indent/module.lua

@@ -149,7 +149,7 @@ module.public = {
     ---@param new_indent number
     buffer_set_line_indent = function(buffer, start_row, new_indent)
         local line = vim.api.nvim_buf_get_lines(buffer, start_row, start_row + 1, true)[1]
-        if line:match("^%s*$") then
+        if line:match("^%s*$") or new_indent == -1 then
             return
         end