fix: parameter appending for number types

Updated string and number parameter handling to ensure proper conversion to string before appending.

Author: jef

modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-ktor/api.mustache

@@ -72,7 +72,7 @@ import com.fasterxml.jackson.databind.ObjectMapper
                         {{{paramName}}}?.apply { append("{{{baseName}}}", {{{paramName}}}.toString()) }
                         {{/isNumber}}
                         {{#isNumber}}
-                        {{{paramName}}}?.apply { append("{{{baseName}}}", {{{paramName}}}) }
+                        {{{paramName}}}?.apply { append("{{{baseName}}}", {{{paramName}}}.toString()) }
                         {{/isNumber}}
                         {{/isString}}
                         {{#isString}}
@@ -101,7 +101,7 @@ import com.fasterxml.jackson.databind.ObjectMapper
                         {{{paramName}}}?.apply { it.append("{{{baseName}}}", {{{paramName}}}.toString()) }
                         {{/isNumber}}
                         {{#isNumber}}
-                        {{{paramName}}}?.apply { it.append("{{{baseName}}}", {{{paramName}}}) }
+                        {{{paramName}}}?.apply { it.append("{{{baseName}}}", {{{paramName}}}.toString()) }
                         {{/isNumber}}
                         {{/isString}}
                         {{#isString}}