Trim baseline selection

Refs vimeo#6000

src/Psalm/ErrorBaseline.php

@@ -282,12 +282,7 @@ function (string $extension): string {
 
                 foreach ($existingIssueType['s'] as $selection) {
                     $codeNode = $baselineDoc->createElement('code');
-
-                    /** @todo in major version release (e.g. Psalm 5) replace $selection with trim($selection)
-                     * This will be a minor BC break as baselines generated will then not be compatible with Psalm
-                     * versions from before PR https://github.com/vimeo/psalm/pull/6000
-                     */
-                    $codeNode->textContent = $selection;
+                    $codeNode->textContent = trim($selection);
                     $issueNode->appendChild($codeNode);
                 }
                 $fileNode->appendChild($issueNode);