当请求没有body时, 移除content-type, 保持与原生一致

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@bytedo/fetch",
-  "version": "2.1.2",
+  "version": "2.1.3",
   "description": "全新的ajax封装。分2个版本, 一个基于XMLHttpRequest, 一个基于window.fetch",
   "main": "dist/index.js",
   "files": [

src/index.js

@@ -146,7 +146,10 @@ class _Request {
             }
           }
       }
+    } else {
+      delete options.headers['content-type']
     }
+
     if (hasAttach) {
       delete options.headers['content-type']
     }

src/next.js

@@ -122,7 +122,10 @@ class _Request {
           }
           break
       }
+    } else {
+      delete options.headers['content-type']
     }
+
     if (hasAttach) {
       delete options.headers['content-type']
     }