fix(deps): update dependency postcss-selector-parser to v7 (#888)

This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
|
[postcss-selector-parser](https://redirect.github.com/postcss/postcss-selector-parser)
| [`^6.1.0` ->
`^7.0.0`](https://renovatebot.com/diffs/npm/postcss-selector-parser/6.1.2/7.0.0)
|
[![age](https://developer.mend.io/api/mc/badges/age/npm/postcss-selector-parser/7.0.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![adoption](https://developer.mend.io/api/mc/badges/adoption/npm/postcss-selector-parser/7.0.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![passing](https://developer.mend.io/api/mc/badges/compatibility/npm/postcss-selector-parser/6.1.2/7.0.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![confidence](https://developer.mend.io/api/mc/badges/confidence/npm/postcss-selector-parser/6.1.2/7.0.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|

---

### Release Notes

<details>
<summary>postcss/postcss-selector-parser
(postcss-selector-parser)</summary>

###
[`v7.0.0`](https://redirect.github.com/postcss/postcss-selector-parser/blob/HEAD/CHANGELOG.md#700)

[Compare
Source](https://redirect.github.com/postcss/postcss-selector-parser/compare/v6.1.2...v7.0.0)

-   Feat: make insertions during iteration safe (major)

</details>

---

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packages/eslint-plugin-svelte/package.json

@@ -64,7 +64,7 @@
     "postcss": "^8.4.38",
     "postcss-load-config": "^3.1.4",
     "postcss-safe-parser": "^6.0.0",
-    "postcss-selector-parser": "^6.1.0",
+    "postcss-selector-parser": "^7.0.0",
     "semver": "^7.6.2",
     "svelte-eslint-parser": "^1.0.0-0"
   },