Remove stephpy/vim-yaml syntax

It causes issues:
- dracula/vim#163
- stephpy/vim-yaml#22

README.md

@@ -7,7 +7,7 @@ A collection of language packs for Vim.
 > One to rule them all, one to find them, one to bring them all and in the darkness bind them.
 
 - It **won't affect your startup time**, as scripts are loaded only on demand\*.
-- It **installs and updates 120+ times faster** than the <!--Package Count-->192<!--/Package Count--> packages it consists of.
+- It **installs and updates 120+ times faster** than the <!--Package Count-->191<!--/Package Count--> packages it consists of.
 - It is more secure because scripts loaded for all extensions are generated by vim-polyglot (ftdetect).
 - Solid syntax and indentation support (other features skipped). Only the best language packs.
 - All unnecessary files are ignored (like enormous documentation from php support).
@@ -229,7 +229,6 @@ If you need full functionality of any plugin, please use it directly with your p
 - [xdc](https://github.com/amal-khailtash/vim-xdc-syntax)
 - [xml](https://github.com/amadeus/vim-xml)
 - [xsl](https://github.com/vim-scripts/XSLT-syntax)
-- [yaml-extras](https://github.com/stephpy/vim-yaml)
 - [yaml](https://github.com/vim/vim/tree/df44a27b53586fccfc6a3aedc89061fdd9a515ff/runtime)
 - [yard](https://github.com/sheerun/vim-yardoc)
 - [zephir](https://github.com/xwsoul/vim-zephir)

packages.yaml

@@ -1661,11 +1661,6 @@ filetypes:
   - fish_read_history
   ignored_filenames:
   - '~/.config/fish/fish_{read_,}history'
----
-name: yaml-extras
-remote: stephpy/vim-yaml
-after: yaml
-filetypes: []
 # Ansible needs to be after YAML
 ---
 name: ansible