Bump stylelint from 14.16.1 to 15.10.1 in /backend (#1436)

* Bump stylelint from 14.16.1 to 15.10.1 in /backend

Bumps [stylelint](https://github.com/stylelint/stylelint) from 14.16.1 to 15.10.1.
- [Release notes](https://github.com/stylelint/stylelint/releases)
- [Changelog](https://github.com/stylelint/stylelint/blob/main/CHANGELOG.md)
- [Commits](stylelint/stylelint@14.16.1...15.10.1)

---
updated-dependencies:
- dependency-name: stylelint
  dependency-type: direct:development
...

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

* remove obsolete peer deps, setup prettier on its own

* add stylelintignore and address some scss linting warnings

* stylelint matching pattern

* prettier updates

* more prettierignore

* run fix-prettier

* one more linting fix

* Only check styles the team is editing directly

* Use prefix notation for media queries

Stylelint's default rule for media query syntax uses
the newer context notation. However, that syntax requires
[fairly recent browsers](https://caniuse.com/mdn-css_at-rules_media_or_syntax).

* Fix stylelint path

* revert prettier changes

* remove prettierignore and prettier jobs

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Alex Steel <alexander.steel@gsa.gov>
Co-authored-by: danswick <daniel.swick@gsa.gov>
Co-authored-by: Matt Henry <hey@matthenry.fyi>

backend/.stylelintignore

@@ -0,0 +1,3 @@
+**/uswds
+static/compiled/**
+.lighthouseci/**

backend/.stylelintrc.json

@@ -1,12 +1,9 @@
 {
-  "extends": [
-    "stylelint-config-standard",
-    "stylelint-config-standard-scss",
-    "stylelint-config-prettier"
-  ],
+  "extends": ["stylelint-config-standard", "stylelint-config-standard-scss"],
   "rules": {
     "selector-class-pattern": null,
     "no-descending-specificity": null,
-    "function-no-unknown": null
+    "function-no-unknown": null,
+    "media-feature-range-notation": "prefix"
   }
 }