Update dependency postcss to v8.5.15 (#473)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

yarn.lock

@@ -3890,7 +3890,7 @@ mute-stream@^3.0.0:
   resolved "https://registry.yarnpkg.com/mute-stream/-/mute-stream-3.0.0.tgz#cd8014dd2acb72e1e91bb67c74f0019e620ba2d1"
   integrity sha512-dkEJPVvun4FryqBmZ5KhDo0K9iDXAwn08tMLDinNdRBNPcYEDiWYysLcc6k3mjTMlbP9KyylvRpd4wFtwrT9rw==
 
-nanoid@^3.3.11:
+nanoid@^3.3.12:
   version "3.3.12"
   resolved "https://registry.yarnpkg.com/nanoid/-/nanoid-3.3.12.tgz#ab3d912e217a6d0a514f00a72a16543a28982c05"
   integrity sha512-ZB9RH/39qpq5Vu6Y+NmUaFhQR6pp+M2Xt76XBnEwDaGcVAqhlvxrl3B2bKS5D3NH3QR76v3aSrKaF/Kiy7lEtQ==
@@ -4363,11 +4363,11 @@ postcss-value-parser@^4.0.0, postcss-value-parser@^4.1.0, postcss-value-parser@^
   integrity sha512-1NNCs6uurfkVbeXG4S8JFT9t19m45ICnif8zWLd5oPSZ50QnwMfK+H3jv408d4jw/7Bttv5axS5IiHoLaVNHeQ==
 
 postcss@^8.4.40, postcss@^8.5.6:
-  version "8.5.14"
-  resolved "https://registry.yarnpkg.com/postcss/-/postcss-8.5.14.tgz#a66c2d7808fadf69ebb5b84a03f8bafd76c4919c"
-  integrity sha512-SoSL4+OSEtR99LHFZQiJLkT59C5B1amGO1NzTwj7TT1qCUgUO6hxOvzkOYxD+vMrXBM3XJIKzokoERdqQq/Zmg==
+  version "8.5.15"
+  resolved "https://registry.yarnpkg.com/postcss/-/postcss-8.5.15.tgz#d1eaf677a324e9ec02196da2d3fecf4a0b9a735c"
+  integrity sha512-FfR8sjd4em2T6fb3I2MwAJU7HWVMr9zba+enmQeeWFfCbm+UOC/0X4DS8XtpUTMwWMGbjKYP7xjfNekzyGmB3A==
   dependencies:
-    nanoid "^3.3.11"
+    nanoid "^3.3.12"
     picocolors "^1.1.1"
     source-map-js "^1.2.1"