Fix TS compilation error due to needless file-entry-cache import (#…

…6393)

This type import was added in #6356, but during code review that PR was refactored to obviate the `file-entry-cache` types in the public API. The import was never removed. Keeping the import here results in [compilation errors](https://app.circleci.com/pipelines/github/palantir/blueprint/3156/workflows/9eda97ec-3a2f-4aa6-aa6c-89d5b65b8491/jobs/61694) for downstream consumers:

```
../../node_modules/stylelint/types/stylelint/index.d.ts:5:39 - error TS7016: Could not find a declaration file for module 'file-entry-cache'. '/home/circleci/project/node_modules/file-entry-cache/cache.js' implicitly has an 'any' type.
  Try `npm i --save-dev @types/file-entry-cache` if it exists or add a new declaration (.d.ts) file containing `declare module 'file-entry-cache';`

5  import type * as fileEntryCache from 'file-entry-cache'
```

.changeset/fix-unused-type-import.md

@@ -0,0 +1,5 @@
+---
+"stylelint": patch
+---
+
+Fixed: TS compilation error due to needless `file-entry-cache` import

types/stylelint/index.d.ts

@@ -2,7 +2,6 @@ declare module 'stylelint' {
 	import type * as PostCSS from 'postcss';
 	import type { GlobbyOptions } from 'globby';
 	import type { cosmiconfig } from 'cosmiconfig';
-	import type * as fileEntryCache from 'file-entry-cache';
 
 	namespace stylelint {
 		export type Severity = 'warning' | 'error';