fix tests

src/test/java/cc/fascinated/backend/PasteControllerTests.java

@@ -22,7 +22,7 @@ class PasteControllerTests {
     public void ensureUploadSuccess() throws Exception {
         ResultActions result = mockMvc.perform(post("/upload")
                 .accept(MediaType.APPLICATION_JSON)
-                .contentType(MediaType.APPLICATION_JSON)
+                .contentType(MediaType.TEXT_PLAIN)
                 .content("joe"))
                 .andExpect(status().isOk());
     }