[Julia] Fix docstring parameter formatting with backticks

Wrap parameter names in backticks in generated Julia client docstrings
to prevent markdown from misinterpreting underscores as italic formatting.

This fixes an issue where parameter names like `pet_id`, `api_key`, and
`additional_metadata` would render incorrectly in documentation, with
underscores being treated as markdown italic markers instead of literal
characters.

Related issue: JuliaComputing/OpenAPI.jl#72

Author: asinghvi17

modules/openapi-generator/src/main/resources/julia-client/api.mustache

@@ -89,7 +89,7 @@ end
 {{/summary.length}}{{#notes.length}}{{{notes}}}
 
 {{/notes.length}}Params:
-{{#allParams}}- {{paramName}}::{{#isBinary}}{{#isFile}}{{dataType}}{{/isFile}}{{^isFile}}Vector{UInt8}{{/isFile}}{{/isBinary}}{{^isBinary}}{{dataType}}{{/isBinary}}{{#required}} (required){{/required}}
+{{#allParams}}- `{{paramName}}`::{{#isBinary}}{{#isFile}}{{dataType}}{{/isFile}}{{^isFile}}Vector{UInt8}{{/isFile}}{{/isBinary}}{{^isBinary}}{{dataType}}{{/isBinary}}{{#required}} (required){{/required}}
 {{/allParams}}
 
 Return: {{#returnType}}{{returnType}}{{/returnType}}{{^returnType}}Nothing{{/returnType}}, OpenAPI.Clients.ApiResponse