build(deps): bump postcss from 8.5.15 to 8.5.23 in /web/explorer

Bumps [postcss](https://github.com/postcss/postcss) from 8.5.15 to 8.5.23.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](https://github.com/postcss/postcss/compare/8.5.15...8.5.23)

---
updated-dependencies:
- dependency-name: postcss
  dependency-version: 8.5.23
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>

web/explorer/package-lock.json

@@ -2753,9 +2753,9 @@
             "license": "MIT"
         },
         "node_modules/nanoid": {
-            "version": "3.3.12",
-            "resolved": "https://registry.npmjs.org/nanoid/-/nanoid-3.3.12.tgz",
-            "integrity": "sha512-ZB9RH/39qpq5Vu6Y+NmUaFhQR6pp+M2Xt76XBnEwDaGcVAqhlvxrl3B2bKS5D3NH3QR76v3aSrKaF/Kiy7lEtQ==",
+            "version": "3.3.16",
+            "resolved": "https://registry.npmjs.org/nanoid/-/nanoid-3.3.16.tgz",
+            "integrity": "sha512-bzlKTyNJ7+LdGIIwy8ijFpIqEQIvafahV7eYykJ8Cvh42EdJeODoJ6gUJXpQJvej1BddH8OqTXZNE/KfbWAu8Q==",
             "funding": [
                 {
                     "type": "github",
@@ -2986,9 +2986,9 @@
             "integrity": "sha512-FZR9QT60vtE1ocdSIfop+zDIJEoy1lejwOvAjTSy+AmE4GZ//rW1nnIXwCRv4o9ejfzWq++lQMu6FJf9G+NtFg=="
         },
         "node_modules/postcss": {
-            "version": "8.5.15",
-            "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.5.15.tgz",
-            "integrity": "sha512-FfR8sjd4em2T6fb3I2MwAJU7HWVMr9zba+enmQeeWFfCbm+UOC/0X4DS8XtpUTMwWMGbjKYP7xjfNekzyGmB3A==",
+            "version": "8.5.23",
+            "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.5.23.tgz",
+            "integrity": "sha512-g50586zr4bZmwFiTlflMu8E0bDTb5I5gertgwAKmsdUlTQIhZtunzUlD1WSzwcVWPoAVpsrA6vlfCD7oXvRwgg==",
             "funding": [
                 {
                     "type": "opencollective",
@@ -3005,7 +3005,7 @@
             ],
             "license": "MIT",
             "dependencies": {
-                "nanoid": "^3.3.12",
+                "nanoid": "^3.3.16",
                 "picocolors": "^1.1.1",
                 "source-map-js": "^1.2.1"
             },