grammar: add text-transform attribute

Closes #11

grammar.js

@@ -265,7 +265,8 @@ module.exports = grammar({
         "link",
         "italic",
         "bold",
-        "underline"
+        "underline",
+        "text-transform"
       ),
 
     _text_attr_key: ($) => "near",

src/grammar.json

@@ -1086,6 +1086,10 @@
         {
           "type": "STRING",
           "value": "underline"
+        },
+        {
+          "type": "STRING",
+          "value": "text-transform"
         }
       ]
     },

src/node-types.json

@@ -520,6 +520,10 @@
     "type": "target-arrowhead",
     "named": false
   },
+  {
+    "type": "text-transform",
+    "named": false
+  },
   {
     "type": "tooltip",
     "named": false

test/corpus/attributes.txt

@@ -57,6 +57,7 @@ foo.style.shadow: false
 foo.style.multiple: true
 foo.style.animated: true
 foo.style.link: https://to
+foo.style.text-transform: uppercase
 
 --------------------------------------------------------------------------------
 
@@ -72,6 +73,7 @@ foo.style.link: https://to
   (shape (shape_key) (dot) (attribute (attr_key) (dot) (attribute (attr_key) (attr_value (boolean)))))
   (shape (shape_key) (dot) (attribute (attr_key) (dot) (attribute (attr_key) (attr_value (boolean)))))
   (shape (shape_key) (dot) (attribute (attr_key) (dot) (attribute (attr_key) (attr_value))))
+  (shape (shape_key) (dot) (attribute (attr_key) (dot) (attribute (attr_key) (attr_value))))
 )
 
 ================================================================================
@@ -89,6 +91,7 @@ foo.style: {
   multiple: true
   animated: true
   link: https://to
+  text-transform: uppercase
 }
 
 --------------------------------------------------------------------------------
@@ -110,6 +113,7 @@ foo.style: {
         (attribute (attr_key) (attr_value (boolean)))
         (attribute (attr_key) (attr_value (boolean)))
         (attribute (attr_key) (attr_value))
+        (attribute (attr_key) (attr_value))
       )
     )
   )