Update dev-dependencies

Author: wooorm

package.json

@@ -37,17 +37,17 @@
     "is-hidden": "^1.1.0",
     "mdast-util-assert": "^1.0.0",
     "negate": "^1.0.0",
-    "nyc": "^11.0.0",
+    "nyc": "^12.0.0",
     "rehype-parse": "^4.0.0",
-    "remark-cli": "^4.0.0",
-    "remark-parse": "^4.0.0",
-    "remark-preset-wooorm": "^3.0.0",
-    "remark-stringify": "^4.0.0",
+    "remark-cli": "^5.0.0",
+    "remark-parse": "^5.0.0",
+    "remark-preset-wooorm": "^4.0.0",
+    "remark-stringify": "^5.0.0",
     "tape": "^4.6.3",
-    "unified": "^6.1.0",
+    "unified": "^7.0.0",
     "unist-builder": "^1.0.2",
     "unist-util-remove-position": "^1.1.0",
-    "xo": "^0.18.1"
+    "xo": "^0.21.0"
   },
   "scripts": {
     "build": "remark *.md -qfo",