Problem in detection of lang: in yaml front matter

[GuillaumeAllain]

Describe the bug
In the case where lang: language where language is not in quotes, the yaml parsers seems to take on all following options as a language: 'language\nfollowingtitle: option\n'

Steps to reproduce
Steps to reproduce the behavior:

1. Create document with some options after lang: language in yaml front matter. The language shouldn't be encased in quotes
2. ltex can't initialize because the language is not recognized

Expected behavior
Only us language string and stop at newline

Sample document

---
lang: en
title: This is a test
---

Text.

LTeX LS log

 `ERROR][2022-02-16 10:48:51] .../vim/lsp/rpc.lua:420    "rpc"   "/Users/guillaumeallain/.local/share/nvim/lsp_servers/ltex/ltex-ls/bin/ltex-ls" "stderr"        "févr. 16, 2022 10:48:51 A.M. org.bsplines.ltexls.languagetool.LanguageToolJavaInterface <init>\nGRAVE: 'en\ntitle: This is a test' is not a recognized language. Leaving LanguageTool uninitialized, checking disabled.\n"`

Version information
List here the version information of the relevant software.

• Operating system: macOS 11.6.3
• ltex-ls: 15.2.0

Additional context/information

This works without problem when the language string is between quotes. By looking at tests, this doesn't seem like something that can be seen by the current tests for the yaml front matter

[GuillaumeAllain]

The problem seems to be coming from regex which doesn't match new line in the case where there is no quotes:

ltex-ls/src/main/kotlin/org/bsplines/ltexls/parsing/markdown/MarkdownFragmentizer.kt

Line 55 in 13af12b

"\\A---[ \t]*$.*?^lang:[ \t]+(?:\"(.+)\"|'(.+)'|(.+))$.*?^---[ \t]*$",

The regex:
"\\A---[ \t]*$.*?^lang:[ \t]+(?:\"(.+)\"|'(.+)'|(.+))$.*?^---[ \t]*$"

Should be replaced by:
"\\A---[ \t]*$.*?^lang:[ \t]+(?:\"(.+)\"|'(.+)'|([^\n]+))$.*?^---[ \t]*$"

To catch everything between lang: and the newline

However I have not tested this solution and a test should be added to catch this behaviour

[github-actions]

This issue is now fixed on develop. The fix will be included in the next release of LT_EX.

If you don't want to wait, you can try out the nightly pre-release tomorrow. Nightly pre-releases are published every morning at around 4am UTC.