build: update dependency postcss to v8.4.18

(cherry picked from commit e7189f6)

Author: angular-robot

package.json

@@ -184,7 +184,7 @@
     "pidusage": "^3.0.0",
     "piscina": "3.2.0",
     "popper.js": "^1.14.1",
-    "postcss": "8.4.17",
+    "postcss": "8.4.18",
     "postcss-import": "15.0.0",
     "postcss-loader": "7.0.1",
     "prettier": "^2.0.0",

packages/angular_devkit/build_angular/package.json

@@ -47,7 +47,7 @@
     "ora": "5.4.1",
     "parse5-html-rewriting-stream": "6.0.1",
     "piscina": "3.2.0",
-    "postcss": "8.4.17",
+    "postcss": "8.4.18",
     "postcss-import": "15.0.0",
     "postcss-loader": "7.0.1",
     "regenerator-runtime": "0.13.9",

yarn.lock

@@ -8525,6 +8525,15 @@ postcss@8.4.17, postcss@^8.2.14, postcss@^8.3.7, postcss@^8.4.16, postcss@^8.4.7
     picocolors "^1.0.0"
     source-map-js "^1.0.2"
 
+postcss@8.4.18:
+  version "8.4.18"
+  resolved "https://registry.yarnpkg.com/postcss/-/postcss-8.4.18.tgz#6d50046ea7d3d66a85e0e782074e7203bc7fbca2"
+  integrity sha512-Wi8mWhncLJm11GATDaQKobXSNEYGUHeQLiQqDFG1qQ5UTDPTEvKw0Xt5NsTpktGTwLps3ByrWsBrG0rB8YQ9oA==
+  dependencies:
+    nanoid "^3.3.4"
+    picocolors "^1.0.0"
+    source-map-js "^1.0.2"
+
 prelude-ls@^1.2.1:
   version "1.2.1"
   resolved "https://registry.yarnpkg.com/prelude-ls/-/prelude-ls-1.2.1.tgz#debc6489d7a6e6b0e7611888cec880337d316396"