build(deps): bump tree-sitter-lua to v0.0.18

also update highlight queries

runtime/queries/lua/highlights.scm

@@ -180,13 +180,40 @@
 
 (parameters (identifier) @parameter)
 
-(function_call name: (identifier) @function.call)
-(function_declaration name: (identifier) @function)
+(function_declaration
+  name: [
+    (identifier) @function
+    (dot_index_expression
+      field: (identifier) @function)
+  ])
 
-(function_call name: (dot_index_expression field: (identifier) @function.call))
-(function_declaration name: (dot_index_expression field: (identifier) @function))
+(function_declaration
+  name: (method_index_expression
+    method: (identifier) @method))
 
-(method_index_expression method: (identifier) @method.call)
+(assignment_statement
+  (variable_list .
+    name: [
+      (identifier) @function
+      (dot_index_expression
+        field: (identifier) @function)
+    ])
+  (expression_list .
+    value: (function_definition)))
+
+(table_constructor
+  (field
+    name: (identifier) @function
+    value: (function_definition)))
+
+(function_call
+  name: [
+    (identifier) @function.call
+    (dot_index_expression
+      field: (identifier) @function.call)
+    (method_index_expression
+      method: (identifier) @method.call)
+  ])
 
 (function_call
   (identifier) @function.builtin
@@ -214,7 +241,7 @@
 
 (number) @number
 
-(string) @string @spell
+(string) @string
 
 (escape_sequence) @string.escape