minor symfony#61696 [Finder] Add better type information using PHPDoc (azjezz)

This PR was merged into the 7.4 branch.

Discussion
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 [Finder] Add better type information using PHPDoc

| Q             | A
| ------------- | ---
| Branch?       | 7.4
| Bug fix?      | no
| New feature?  | no <!-- if yes, also update src/**/CHANGELOG.md -->
| Deprecations? | no <!-- if yes, also update UPGRADE-*.md and src/**/CHANGELOG.md -->
| Issues        | N/A <!-- prefix each issue number with "Fix #"; no need to create an issue if none exists, explain below -->
| License       | MIT

Improve type information in `Finder` component

Commits
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4e8e9c9 chore(finder): add better type information using phpdoc

Author: nicolas-grekas

src/Symfony/Component/Finder/Finder.php

@@ -37,7 +37,7 @@
  *
  * @author Fabien Potencier <[email protected]>
  *
- * @implements \IteratorAggregate<string, SplFileInfo>
+ * @implements \IteratorAggregate<non-empty-string, SplFileInfo>
  */
 class Finder implements \IteratorAggregate, \Countable
 {
@@ -657,7 +657,7 @@ public function in(string|array $dirs): static
      *
      * This method implements the IteratorAggregate interface.
      *
-     * @return \Iterator<string, SplFileInfo>
+     * @return \Iterator<non-empty-string, SplFileInfo>
      *
      * @throws \LogicException if the in() method has not been called
      */