Migrate Go server samples to OAS 3 only (#6471)

* migrate go server samples to oas3

* add back pom.xml

samples/server/petstore/go-gin-api-server/go/model_inline_object.go

@@ -0,0 +1,19 @@
+/*
+ * OpenAPI Petstore
+ *
+ * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+ *
+ * API version: 1.0.0
+ * Generated by: OpenAPI Generator (https://openapi-generator.tech)
+ */
+
+package petstoreserver
+
+type InlineObject struct {
+
+	// Updated name of the pet
+	Name string `json:"name,omitempty"`
+
+	// Updated status of the pet
+	Status string `json:"status,omitempty"`
+}

samples/server/petstore/go-gin-api-server/go/model_inline_object_1.go

@@ -0,0 +1,23 @@
+/*
+ * OpenAPI Petstore
+ *
+ * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+ *
+ * API version: 1.0.0
+ * Generated by: OpenAPI Generator (https://openapi-generator.tech)
+ */
+
+package petstoreserver
+
+import (
+	"os"
+)
+
+type InlineObject1 struct {
+
+	// Additional data to pass to server
+	AdditionalMetadata string `json:"additionalMetadata,omitempty"`
+
+	// file to upload
+	File *os.File `json:"file,omitempty"`
+}