vim-patch:9.0.0417: Jsonnet files are not recognized (#20119)

Problem:    Jsonnet files are not recognized.
Solution:   Add a pattern for Jsonnet files. (Cezary Drożak, closes vim/vim#11073,
            closes vim/vim#11081)
2a4c885d54

runtime/lua/vim/filetype.lua

@@ -557,6 +557,8 @@ local extension = {
   ['json-patch'] = 'json',
   json5 = 'json5',
   jsonc = 'jsonc',
+  jsonnet = 'jsonnet',
+  libjsonnet = 'jsonnet',
   jsp = 'jsp',
   jl = 'julia',
   kv = 'kivy',