add io.readChars overload (simpler, less error prone) (#16044)

* add simpler to use readChars overload

* use new readChars overload

* Update lib/wrappers/openssl.nim

Co-authored-by: Andreas Rumpf <rumpf_a@web.de>
Co-authored-by: flywind <xzsflywind@gmail.com>

changelog.md

@@ -66,6 +66,8 @@
 - `os.FileInfo` (returned by `getFileInfo`) now contains `blockSize`,
   determining preferred I/O block size for this file object.
 
+- Added a simpler to use `io.readChars` overload.
+
 - `repr` now doesn't insert trailing newline; previous behavior was very inconsistent,
   see #16034. Use `-d:nimLegacyReprWithNewline` for previous behavior.
 
@@ -167,6 +169,7 @@ provided by the operating system.
   dumping (on select signals) and notifying the parent process about the cause
   of termination.
 
+
 ## Language changes
 
 - `nimscript` now handles `except Exception as e`.