doc: fix type of atime/mtime

PR-URL: #29666
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: exoego

doc/api/fs.md

@@ -2086,8 +2086,8 @@ changes:
 -->
 
 * `fd` {integer}
-* `atime` {integer}
-* `mtime` {integer}
+* `atime` {number|string|Date}
+* `mtime` {number|string|Date}
 
 Synchronous version of [`fs.futimes()`][]. Returns `undefined`.
 
@@ -3462,8 +3462,8 @@ changes:
 -->
 
 * `path` {string|Buffer|URL}
-* `atime` {integer}
-* `mtime` {integer}
+* `atime` {number|string|Date}
+* `mtime` {number|string|Date}
 
 Returns `undefined`.