Update baseClient.mustache for scala-http4s (#21825)

The code for setting the form body parameters were wrong,

e.g. the key value pair (id, 12345) would be encoded as
id=%28id%2C12345%29

This commit adds a fix to the base client to correctly setting formBody values the previous pair will now be encoded as

id=12345

Author: KristianAN

modules/openapi-generator/src/main/resources/scala-http4s/baseClient.mustache

@@ -66,7 +66,7 @@ abstract class BaseClient[F[*]: Concurrent](
         request.putHeaders(Header.Raw(CIString(name), value))
     }
     val formBody = formParameters.map { x =>
-      UrlForm(x.groupBy(_._1).map{case (k, v) => (k, v.mkString(","))}.toSeq*)
+      UrlForm(x.groupBy(_._1).map { case (k, v) => (k, v.map(_._2).mkString(",")) }.toSeq*)
     }
 
     import JsonSupports.*

samples/client/petstore/scala-http4s/src/main/scala/org/openapitools/client/apis/BaseClient.scala

@@ -75,7 +75,7 @@ abstract class BaseClient[F[*]: Concurrent](
         request.putHeaders(Header.Raw(CIString(name), value))
     }
     val formBody = formParameters.map { x =>
-      UrlForm(x.groupBy(_._1).map{case (k, v) => (k, v.mkString(","))}.toSeq*)
+      UrlForm(x.groupBy(_._1).map { case (k, v) => (k, v.map(_._2).mkString(",")) }.toSeq*)
     }
 
     import JsonSupports.*