fix(yaml): yaml: Fix TypeError undefined length (#1229)

In YAML files LSP completion is not happening because
yaml-language-server is failing with error:

    TypeError: Cannot read properties of undefined (reading 'length')

from out/server/src/languageserver/handlers/settingsHandlers.js:78:51,
which it's expecting to have yaml.schemaStore.url.length and it's
doesn't exist.

Signed-off-by: Javier Tia <javier.tia@gmail.com>

lua/lazyvim/plugins/extras/lang/yaml.lua

@@ -38,6 +38,8 @@ return {
                 -- Must disable built-in schemaStore support to use
                 -- schemas from SchemaStore.nvim plugin
                 enable = false,
+                -- Avoid TypeError: Cannot read properties of undefined (reading 'length')
+                url = "",
               },
             },
           },