[Snyk] Security upgrade postcss from 8.4.27 to 8.4.31 (#212)

<p>This PR was automatically created by Snyk using the credentials of a
real user.</p><br /><h3>Snyk has created this PR to fix one or more
vulnerable packages in the `yarn` dependencies of this project.</h3>



#### Changes included in this PR

- Changes to the following files to upgrade the vulnerable dependencies
to a fixed version:
    - webpack/package.json
    - webpack/yarn.lock


#### Note for
[zero-installs](https://yarnpkg.com/features/zero-installs) users

If you are using the Yarn feature
[zero-installs](https://yarnpkg.com/features/zero-installs) that was
introduced in Yarn V2, note that this PR does not update the
`.yarn/cache/` directory meaning this code cannot be pulled and
immediately developed on as one would expect for a zero-install project
- you will need to run `yarn` to update the contents of the
`./yarn/cache` directory.
If you are not using zero-install you can ignore this as your flow
should likely be unchanged.


#### Vulnerabilities that will be fixed
##### With an upgrade:
Severity | Priority Score (*) | Issue | Breaking Change | Exploit
Maturity

:-------------------------:|-------------------------|:-------------------------|:-------------------------|:-------------------------
![medium
severity](https://res.cloudinary.com/snyk/image/upload/w_20,h_20/v1561977819/icon/m.png
"medium severity") | **551/1000** <br/> **Why?** Recently disclosed, Has
a fix available, CVSS 5.3 | Improper Input Validation
<br/>[SNYK-JS-POSTCSS-5926692](https://snyk.io/vuln/SNYK-JS-POSTCSS-5926692)
| No | No Known Exploit

(*) Note that the real score may have changed since the PR was raised.











Check the changes in this PR to ensure they won't cause issues with your
project.



------------



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🧐 [View latest project
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[//]: #
(snyk:metadata:{"prId":"9d90cc17-5029-4ba3-be1c-4ab4d9278178","prPublicId":"9d90cc17-5029-4ba3-be1c-4ab4d9278178","dependencies":[{"name":"postcss","from":"8.4.27","to":"8.4.31"}],"packageManager":"yarn","projectPublicId":"56984b7e-3ced-49b8-b9ff-e1c60f354374","projectUrl":"https://app.snyk.io/org/thejoeejoee/project/56984b7e-3ced-49b8-b9ff-e1c60f354374?utm_source=github&utm_medium=referral&page=fix-pr","type":"auto","patch":[],"vulns":["SNYK-JS-POSTCSS-5926692"],"upgrade":["SNYK-JS-POSTCSS-5926692"],"isBreakingChange":false,"env":"prod","prType":"fix","templateVariants":["updated-fix-title","priorityScore"],"priorityScoreList":[551],"remediationStrategy":"vuln"})

---

**Learn how to fix vulnerabilities with free interactive lessons:**

🦉 [Improper Input
Validation](https://learn.snyk.io/lesson/improper-input-validation/?loc&#x3D;fix-pr)

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"