fix: webpack/package.json & webpack/yarn.lock to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-POSTCSS-5926692

webpack/yarn.lock

@@ -935,9 +935,9 @@ caniuse-lite@^1.0.30001332, caniuse-lite@^1.0.30001517:
   integrity sha512-tahF5O9EiiTzwTUqAeFjIZbn4Dnqxzz7ktrgGlMYNLH43Ul26IgTMH/zvL3DG0lZxBYnlT04axvInszUsZULdA==
 
 caniuse-lite@^1.0.30001538:
-  version "1.0.30001538"
-  resolved "https://registry.yarnpkg.com/caniuse-lite/-/caniuse-lite-1.0.30001538.tgz#9dbc6b9af1ff06b5eb12350c2012b3af56744f3f"
-  integrity sha512-HWJnhnID+0YMtGlzcp3T9drmBJUVDchPJ08tpUGFLs9CYlwWPH2uLgpHn8fND5pCgXVtnGS3H4QR9XLMHVNkHw==
+  version "1.0.30001541"
+  resolved "https://registry.yarnpkg.com/caniuse-lite/-/caniuse-lite-1.0.30001541.tgz#b1aef0fadd87fb72db4dcb55d220eae17b81cdb1"
+  integrity sha512-bLOsqxDgTqUBkzxbNlSBt8annkDpQB9NdzdTbO2ooJ+eC/IQcvDspDc058g84ejCelF7vHUx57KIOjEecOHXaw==
 
 chalk@^2.4.2:
   version "2.4.2"
@@ -2652,6 +2652,15 @@ postcss@^8, postcss@^8.4.21, postcss@^8.4.23, postcss@^8.4.31:
     picocolors "^1.0.0"
     source-map-js "^1.0.2"
 
+postcss@^8.4.31:
+  version "8.4.31"
+  resolved "https://registry.yarnpkg.com/postcss/-/postcss-8.4.31.tgz#92b451050a9f914da6755af352bdc0192508656d"
+  integrity sha512-PS08Iboia9mts/2ygV3eLpY5ghnUcfLV/EXTOW1E2qYxJKGGBUtNjN76FYHnMs36RmARn41bC0AZmn+rR0OVpQ==
+  dependencies:
+    nanoid "^3.3.6"
+    picocolors "^1.0.0"
+    source-map-js "^1.0.2"
+
 process-nextick-args@~2.0.0:
   version "2.0.1"
   resolved "https://registry.yarnpkg.com/process-nextick-args/-/process-nextick-args-2.0.1.tgz#7820d9b16120cc55ca9ae7792680ae7dba6d7fe2"