fix(fs): permit square brackets `[]` in file paths (#21625)

Co-authored-by: Sebastian Poxhofer <secustor@users.noreply.github.com>

lib/util/fs/util.spec.ts

@@ -73,6 +73,7 @@ describe('util/fs/util', () => {
     ${'/foo'}           | ${false}
     ${'&&'}             | ${false}
     ${';'}              | ${true}
+    ${'./[foo]/bar'}    | ${true}
   `('isValidPath($value) == $expected', ({ value, expected }) => {
     expect(isValidPath(value, 'cacheDir')).toBe(expected);
   });

lib/util/fs/util.ts

@@ -5,7 +5,7 @@ import { logger } from '../../logger';
 
 // http://www.mtu.edu/umc/services/digital/writing/characters-avoid/
 // We allow spaces, but not newlines
-const restricted = /[[\]#%&<>*?\b\n\r\0!'"|‘“^`]/;
+const restricted = /[#%&<>*?\b\n\r\0!'"|‘“^`]/;
 
 function assertBaseDir(path: string, baseDir: string): void {
   if (!path.startsWith(baseDir)) {