deprecate htmlparser (#22870)

ref https://github.com/nim-lang/Nim/pull/22848
see also https://github.com/nim-lang/htmlparser
will build the documentation later when everything else is settled

---------

Co-authored-by: Andreas Rumpf <rumpf_a@web.de>

changelog.md

@@ -11,6 +11,7 @@
 
 - Changed `std/osfiles.copyFile` to allow to specify `bufferSize` instead of a hardcoded one.
 - Changed `std/osfiles.copyFile` to use `POSIX_FADV_SEQUENTIAL` hints for kernel-level aggressive sequential read-aheads.
+- `std/htmlparser` has been moved to a nimble package, use `nimble` or `atlas` to install it.
 
 [//]: # "Additions:"
 

lib/pure/htmlparser.nim

@@ -47,6 +47,8 @@
 ##     writeFile("output.html", $html)
 ##   ```
 
+{.deprecated: "use `nimble install htmlparser` and import `pkg/htmlparser` instead".}
+
 import strutils, streams, parsexml, xmltree, unicode, strtabs
 
 when defined(nimPreviewSlimSystem):