build(go): switch to go 1.21 (#2049)

Also update to the latest swaggo version, as the previous one did not work with go 1.21

Signed-off-by: Andrei Aaron <aaaron@luxoft.com>

swagger/docs.go

@@ -1,5 +1,4 @@
-// Code generated by swaggo/swag. DO NOT EDIT.
-
+// Package swagger Code generated by swaggo/swag. DO NOT EDIT
 package swagger
 
 import "github.com/swaggo/swag"
@@ -1504,6 +1503,8 @@ var SwaggerInfo = &swag.Spec{
 	Description:      "APIs for Open Container Initiative Distribution Specification",
 	InfoInstanceName: "swagger",
 	SwaggerTemplate:  docTemplate,
+	LeftDelim:        "{{",
+	RightDelim:       "}}",
 }
 
 func init() {