update dependencies

package.json

@@ -8,39 +8,39 @@
   },
   "bugs": "https://github.com/static-dev/spike-css-standards/issues",
   "dependencies": {
-    "autoprefixer": "^7.1.2",
+    "autoprefixer": "^8.3.0",
     "cssnano": "^3.7.4",
     "postcss-attribute-case-insensitive": "^2.0.0",
-    "postcss-calc": "^6.0.0",
-    "postcss-color-function": "^4.0.0",
-    "postcss-color-gray": "^4.0.0",
+    "postcss-calc": "^6.0.1",
+    "postcss-color-function": "^4.0.1",
+    "postcss-color-gray": "^4.1.0",
     "postcss-color-hex-alpha": "^3.0.0",
     "postcss-color-hsl": "^2.0.0",
     "postcss-color-hwb": "^3.0.0",
     "postcss-color-rebeccapurple": "^3.0.0",
     "postcss-color-rgb": "^2.0.0",
     "postcss-custom-media": "^6.0.0",
-    "postcss-custom-properties": "^6.1.0",
+    "postcss-custom-properties": "^7.0.0",
     "postcss-custom-selectors": "^4.0.1",
-    "postcss-font-family-system-ui": "^2.0.1",
+    "postcss-font-family-system-ui": "^3.0.0",
     "postcss-font-variant": "^3.0.0",
-    "postcss-image-set-polyfill": "^0.4.3",
+    "postcss-image-set-polyfill": "^0.4.4",
     "postcss-import": "^11.0.0",
     "postcss-media-minmax": "^3.0.0",
-    "postcss-nesting": "^4.0.1",
+    "postcss-nesting": "^5.0.0",
     "postcss-property-lookup": "^2.0.0",
     "postcss-pseudo-class-any-link": "^4.0.0",
     "postcss-selector-matches": "^3.0.1",
     "postcss-selector-not": "^3.0.1",
-    "rucksack-css": "^0.9.1"
+    "rucksack-css": "^1.0.2"
   },
   "devDependencies": {
-    "ava": "^0.22.0",
-    "coveralls": "^2.13.1",
-    "nyc": "^11.0.3",
-    "rewire": "^2.5.2",
-    "snazzy": "^7.0.0",
-    "standard": "^10.0.2"
+    "ava": "^0.25.0",
+    "coveralls": "^3.0.0",
+    "nyc": "^11.7.1",
+    "rewire": "^4.0.1",
+    "snazzy": "^7.1.1",
+    "standard": "^11.0.1"
   },
   "engines": {
     "node": ">= 6"