Restore disabled grammars

This change reverts <helix-editor#9316>,
which disables grammars hosted on sr.ht. The outage of sr.ht on January
2024 had been addressed and its post-mortem was published on their blog.

This reverts commit 17dd102.

Reference: https://sourcehut.org/blog/2024-01-19-outage-post-mortem/

languages.toml

@@ -1,8 +1,6 @@
 # Language support configuration.
 # See the languages documentation: https://docs.helix-editor.com/master/languages.html
 
-use-grammars = { except = [ "hare", "wren", "gemini" ] }
-
 [language-server]
 
 als = { command = "als" }