[chore] devops: add languages config for helix editor

The default Helix configuration for Python is different,
so the pylint warnings aren't shown and the formatter
re-formats files by accident when you edit an existing file.

Therefore, this commit adds `python` language configuration
to ease developing SearXNG with Helix Editor [^1].

[^1]: https://helix-editor.com

.helix/languages.toml

@@ -0,0 +1,10 @@
+[[language]]
+name = "python"
+language-servers = ["basedpyright", "pylsp"]
+formatter = { command = "black", args = [
+    "--target-version",
+    "py311",
+    "--line-length",
+    "120",
+    "--skip-string-normalization",
+] }