update custom MultipartBody to use MediaType.parse() method instead of depending the MediaType.get() in okhttp 3.11.0 and higher version.

Author: gawen957

library/src/main/java/com/qiniu/android/http/MultipartBody.java

@@ -38,34 +38,34 @@ public final class MultipartBody extends RequestBody {
      * need to be bundled in a particular order. Any "multipart" subtypes that an implementation does
      * not recognize must be treated as being of subtype "mixed".
      */
-    public static final MediaType MIXED = MediaType.get("multipart/mixed");
+    public static final MediaType MIXED = MediaType.parse("multipart/mixed");
 
     /**
      * The "multipart/alternative" type is syntactically identical to "multipart/mixed", but the
      * semantics are different. In particular, each of the body parts is an "alternative" version of
      * the same information.
      */
-    public static final MediaType ALTERNATIVE = MediaType.get("multipart/alternative");
+    public static final MediaType ALTERNATIVE = MediaType.parse("multipart/alternative");
 
     /**
      * This type is syntactically identical to "multipart/mixed", but the semantics are different. In
      * particular, in a digest, the default {@code Content-Type} value for a body part is changed from
      * "text/plain" to "message/rfc822".
      */
-    public static final MediaType DIGEST = MediaType.get("multipart/digest");
+    public static final MediaType DIGEST = MediaType.parse("multipart/digest");
 
     /**
      * This type is syntactically identical to "multipart/mixed", but the semantics are different. In
      * particular, in a parallel entity, the order of body parts is not significant.
      */
-    public static final MediaType PARALLEL = MediaType.get("multipart/parallel");
+    public static final MediaType PARALLEL = MediaType.parse("multipart/parallel");
 
     /**
      * The media-type multipart/form-data follows the rules of all multipart MIME data streams as
      * outlined in RFC 2046. In forms, there are a series of fields to be supplied by the user who
      * fills out the form. Each field has a name. Within a given form, the names are unique.
      */
-    public static final MediaType FORM = MediaType.get("multipart/form-data");
+    public static final MediaType FORM = MediaType.parse("multipart/form-data");
 
     private static final byte[] COLONSPACE = {':', ' '};
     private static final byte[] CRLF = {'\r', '\n'};